LEE- Gıda Mühendisliği Lisansüstü Programı

Bu topluluk için Kalıcı Uri

http://hdl.handle.net/11527/19292

Gözat

Phenolic and carotenoid profiles of tomatoes collected from different parts of Turkey and antioxidant properties of dried tomatoes

(Graduate School, 2021-02-18) Bakır, Sena ; Çapanoğlu, Güven, Esra ; 506132509 ; Food Engineering ; Gıda Mühendisliği

Tomatoes, which are the indispensable part of the Mediterranean diet, have attracted the attention of several researchers due to being one of the most consumed fruit all around the world. Tomato may be consumed as fresh and also in forms of processed products including paste, sauce, juice, etc. Tomato consumption is associated with reducing the risk of cardiovascular diseases, blood sugar, obesity, and also decreasing the carcinogenic cells in the human body which has been attributed to their high phenolic and carotenoid contents. Considering the health effects of tomato bioactives, phenolic and carotenoid profiling of tomatoes using diverse methods have taken the attraction of scientists. The objectives of this Ph.D. thesis were (i) to evaluate the phenolic and carotenoid profiles of some selected Turkish tomato varieties; (ii) to determine the effect of different drying techniques on the phenolic profile of tomatoes and monitoring the bioaccessibility of key phenolic components after simulated in vitro digestion; and (iii) to investigate the phenolic and carotenoid contents of a new functional food by enriching with tomato powder and to elucidate the interactions between these bioactives with proteins. Regarding these aims, first a comprehensive review was prepared on the functional properties of tomato and tomato by-products and their possible applications in foods (Chapter 2). In this part, phenolic profiling methods and their applications have been summarized. On the other hand, use of tomatoes and tomato by-products in different foods as functional ingredients was discussed. In the experimental part, firstly tomato landraces of Turkey were investigated, and 77 Turkish labelled tomato seed samples were collected. The obtained seed samples were planted in open fields for two harvest years, but only 50 of them were used for further analyzes. Harvested samples of both years were analyzed for their phenolic profile (Chapter 3), as well as carotenoids and other health-related compounds (Chapter 4). In order to evaluate the effect of drying on tomato bioactives, various drying treatments were applied and also some commercial dried samples were provided to evaluate the changes in their phenolic and carotenoid contents; moreover, bioaccessibility of phenolic compounds after drying was investigated by using a simulated in vitro bioaccessibility protocol (Chapter 5). Finally, a new functional food was produced using tomato powder, and investigated in terms of their phenolics, carotenoids, their interactions with proteins, and in vitro bioaccessibility (Chapter 6). In Chapter 3, the semi-polar metabolite profiling was aimed for Turkish tomato accessions. Tomato seeds were planted in an open field to accomplish this goal. Harvested samples were firstly evaluated for their colour and pH values. Subsequently, samples were ground under liquid nitrogen and dried with a lyophilizator which was followed by storing at -20⁰C for further analysis. Methanol extracts were prepared were phenolic profile determination. LC-MS equipment was used for the research, and outcomes of this analysis were evaluated with PCA and HCA diagrams. Results indicated that the phenolic content of landraces diverse mostly based on the fruit size on the PCA diagram. On the other hand, geographical area of seed samples where they were collected, did not directly affect the semi-polar metabolite content of tomato fruits. In Chapter 4, the biodiversity of potential health-beneficial compounds within a 50 tomato fruit accessions which were collected throughout Turkey, was assessed. The contents of phenolics, carotenoids, ascorbic acid and tocopherols, as well as their antioxidant capacities were investigated for each sample. By using complementary spectrophotometric assays, the antioxidant capacity of both hydrophilic and lipophilic extracts were determined after individual antioxidants were detected by HPLC using an on-line antioxidant detection method. Using HPLC with a photodiode array and fluorescence detection, phenolic acids, flavonoids, carotenoids and vitamins C and E were quantified. The results showed that concerning their hydrophilic and lipophilic antioxidants, there is a large variety within this set of samples. In Chapter 5, sun-dried, freeze-dried, semi oven-dried and oven-dried (at 60, 80, 100 and 120⁰C) tomato samples were compared with each other to monitor the influence of drying on phenolic and carotenoid contents, and also on some vitamins. Semi-polar metabolite profile of fruits was determined with LC-MS analysis. Sugar profile of samples was evaluated with RI-HPLC analysis. Individual phenolics and carotenoids were determined with HPLC coupled with PDA and fluorescence detectors, respectively. Despite of these, ergosterol content of smaples were measured with HPLC system. Moreover, in vitro bioaccessibility protocol was applied to understand the changes in phenolics during digestion. Metabolite diversity analysis indicated that semi-polar components in freeze-dried and semi-dried samples were close to each other, while the sun-dried samples were all located together on the PCA diagram as well as the oven-dried ones. These results were in accordance with the data obtained after HCA analysis. In Chapter 6, sun-dried tomato powder was added to simit dough at different concentrations to produce functional simit samples. Phenolic-protein and carotenoid-protein interactions as well as the content of lipophilic and hydrophilic antioxidants were investigated by using flours with different protein contents. For this purpose, 10.4, 11.5 and 13.1% protein containing flours were used to prepare simit doughs and flours in samples were replaced with 2, 4 and 8% tomato powder for the preparation of functional simit samples. The semi-polar metabolite contents of samples were analyzed by LC-MS and lipophilic compounds were determined with HPLC-PDA coupled with fluorescence detector. Metabolite profiles of samples prepared with 11.5% and 13.1% protein containing flour were found to be close to each other while 10.4% protein containing flour showed a different trend. The difference in t-lycopene content between samples were found to be statistically significant, having the highest levels in samples containing the highest levels of protein flour, whereas this difference was not significant in the case of β-carotene. According to the results of hydrophilic compounds, chlorogenic acid content in 13.1% protein flour and 8% tomato powder containing simit samples were found to be 4.7 times higher compared to its counterpart prepared with 2% tomato powder. According to the in vitro bioaccessibility results, the highest recovery value for chlorogenic acid was obtained with 13.1% protein flour and 4% tomato powder containing simit sample (44%) covered with sesame. In Chapter 7, the final part, all results obtained within this work were evaluated together, conclusions and recommendations for future research are provided. The main conclusions derived in each section were summarized including the changes in phenolic and carotenoid profiles of tomato samples, effect of simulated gastrointestinal digestion on the bioactives of tomatoes, changes in tomato bioactives during drying with different methods, and interaction of phenolics and carotenoids with proteins observed in a traditional bakery product. Finally, suggestions on the potential future work were provided.
Encapsulation and release of amino acids in double emulsions

(Graduate School, 2021-03-18) Kocaman, Esra ; Van Der Meeren, Paul ; 506162503 ; Food Engineering ; Gıda Mühendisliği

Double emulsions have been studied for many years, given their potential as encapsulation systems. It is also possible to control the release of diverse bioactive components by means of double emulsions. As amino acids might be degraded to some extent due to environmental factors such as pH, temperature, light exposure as well as some reactions (i.e. oxidation, Maillard), their encapsulation may be advantageous to avoid these issues. Besides, encapsulation may enable to release of these compounds in a later stage of the gastro-intestinal tract. The main research question of our research project was to what extent the release of encapsulated components from double emulsions can be controlled by the emulsification method, emulsion composition and environmental factors. Moreover, it was evaluated whether the release kinetics were substantially influenced by the molecular properties of the encapsulated compounds. Hence, this thesis studies the influence of some parameters on double emulsion stability as well as amino acid encapsulation and release in double emulsions. The current study consist of the evaluation of these parameters: solute characteristics (i.e hydrophobicity, molar mass) and concentration, pH of the aqueous phases, hydrophobic and hydrophilic emulsifier, homogenization and thickener. For the investigation of the effect of these parameters, the emulsion droplet size, and the entrapped water volume fraction were evaluated to characterize the double emulsions. Moreover, the release of amino acids was observed during storage using spectrophotometric and Nuclear Magnetic Resonance (NMR) techniques. A modification of the original method was performed to enable the optimum conditions for amino acid quantification (section 4.1). Due to the high background absorbance of the reagent 2,4,6-trinitrobenzenesulfonic acid (TNBS) which was the case for many of the measured concentrations, different TNBS concentrations were evaluated in order to determine the optimum concentration. Hence, the solution containing 0.6 mM TNBS was choosen as it demonstrated the lowest absorbance among the studied concentrations as a blank and the TNBS solution reacted with leucine. As the absorbance was not substantially changed after 3 hours, it was used as the reaction time. In section 4.2, the effect of solute characteristics on double emulsion stability and release of encapsulated compounds were presented. Different amino acids (i.e. hydrophilic and hydrophobic) were used to investigate the hydrophobicity effect at different temperatures. Also, di-peptides were used as encapsulated compound in order to evaluate the influence of molecular mass. The results showed that an increase was observed from 50 up to 90 μm in the average droplet size for the samples homogenized with Ultra-turrax at 17500 rpm within the 32 days time frame. The double emulsions at 4 °C indicated a higher increase in average droplet size as compared to 37 °C. To investigate the main instability mechanism in the emulsion, double emulsions were diluted with sodium dodecyl sulfate (SDS) before laser diffraction measurement. The measurement of the droplet size in the presence of SDS showed that flocculation was the main instability mechanism, which caused an increase in droplet size. On the other hand, a constant enclosed water volume fraction was found in double emulsions during 16 days of storage, independent from the temperature and hydrophobicity studied in this thesis. The encapsulation efficiency of amino acids in the inner water droplets was found to be higher than 80% in all cases. From the release results, amino acid hydrophobicity and storage temperature were found to largely influence the release rate of the encapsulated amino acids. The amino acid release rates were fastest at 37 °C, which was the highest temperature examined in this section of the thesis. This can be explained by the higher solubility as well as increased diffusion rate of amino acids in the intermediate phase. Also, an increase was observed in the release rates of amino acids as a result of higher hydrophobicity. The significant effects of hydrophobicity and temperature, as well as the constant enclosed water volume revealed that the release of amino acids from the inner to the outer water phase was mainly governed by a direct diffusion mechanism. As the di-peptides released faster than the amino acids, it follows that the increased solubility overruled the effect from the decreased diffusion coefficient of the dissolved compound in the oil phase. In section 4.3, the influence of solute concentration (i.e. 5, 10, 20 and 40 mM) on the release and double emulsion stability was investigated. The varying concentrations of amino acid did not cause a significant difference in the increase of volume weighed droplet size during 16 days. The entrapped water volume was stable for double emulsions that contained varying solute concentrations except from the double emulsion which contained 40 mM where a decrease was observed through 16 days of storage. This can be a result of the faster diffusion velocity of the amino acid across the oil phase to the external water phase as compared to the diffusion of potassium chloride (KCl) through the oil phase to the internal water phase. Hence, a fraction of the internal phase was expelled to the external water phase to equalize the osmotic pressure which resulted in a decrease in yield of entrapped water volume. Regarding the average residence time (ta) values, the double emulsion that contained the highest solute concentration studied (i.e. 40 mM) in this thesis indicated a faster release as compared to the other samples at 37°C, whereas there was no significant difference among the samples at 4°C. The pH effect of the aqueous phases on the release of amino acids and di-peptides was evaluated in section 4.4. Regarding the average droplet size, there was no significant difference between samples as a function of pH of the aqueous phases. Considering the release, the transport of the amino acids and di-peptides was faster at neutral pH as compared to acidic and basic pH values, which was thought to be due to the increased solute solubility in the oil phase for the zwitterionic (rather than ionic) form of the more hydrophobic molecules at neutral pH. The oil type effect on amino acid release and double emulsion stability was demonstrated in section 4.5 comparing long chain and middle chain triglycerides. The average droplet size of the long chain triglyceride (LCT) containing double emulsions were larger than of the medium chain triglyceride (MCT) containing samples. This can be due to the stronger aggregation of LCT containing samples as a consequence of the higher viscosity of the LCT oil. From the release results, much faster transport of L-leucine was observed through MCT oil as compared to LCT oil due to its higher solubility. Also, the lower viscosity of MCT oil gives rise to a higher diffusivity of dissolved compounds, which may also fasten molecular transport. In section 4.6, the influence of the hydrophobic emulsifier concentration (from 1 to 5%) on the double emulsion stability and release of entrapped amino acids was demonstrated. The entrapped water volume fraction of the polyglycerol polyricinoleate (PGPR) stabilized samples remained around 100% during 32 days of storage, except from the one with only 1% PGPR which had a decreasing yield due to insufficient stabilisation of the internal water droplets. It follows that the use of higher concentrations of PGPR enabled the entrapped water volume to remain constant, whereas a PGPR concentration below the critical micelle concentration (CMC) caused a water flux from the internal to the external phase. The average residence time (ta) of enclosed L-leucine among the PGPR stabilized double emulsions was lowest at the highest PGPR concentration, which indicates the faster release of L-leucine in the presence of an excess of reverse PGPR micelles in the oil phase. The effect of partial replacement of PGPR by native and phosphatidylcholine (PC) depleted lecithin on double emulsion stability and amino acid release was shown in section 4.7. Although a droplet size increase was observed in the PGPR-stabilised double emulsions during storage, the use of 5% of a PGPR-native lecithin (1/1) mixture resulted in a constant droplet size during storage. The used PGPR and PC-depleted lecithin concentration influenced the droplet size of the double emulsions. The lowest droplet size was about 30 µm just after preparation and during storage in double emulsions containing 5% PC-depleted lecithin. This indicates that partial replacement of PGPR can be beneficial in terms of stability of the double emulsion droplet size. Considering the entrapped water volume, the inclusion of PC-depleted lecithin could not facilitate to overcome the instability at too low (i.e. less than 2% in this case) PGPR concentration. In fact, lecithin addition had a negative impact on the etrapped water volume fraction. The average residence time ta, on the other hand, was much lower in PC-depleted lecithin-containing double emulsions as compared to the emulsions with only PGPR. The effect of hydrophilic emulsifier concentration on amino acid release and double emulsion stability was investigated (section 4.8). It was found that the use of a higher Tween 80 concentration facilitated a less pronounced increase in average droplet size during storage. The use of less than 2% Tween 80 concentration seemed to be insufficient to cover the interface between oil and outer aqueous phase. A constant entrapped water volume fraction was obtained during storage regardless of the Tween 80 concentration. Differences in Tween 80 concentration, varying from 0.5 to 2.0%, did not change the release kinetics to a large extent. In section 4.9, the influence of microfluidization (at 0.75 and 1.00 bar of driving compressed air pressure) and rotor stator homogenization treatment (at 17500, 21500 and 24000 rpm of Ultra-turrax) and the presence of xanthan gum were investigated. Considering the particle size distribution, multimodal and monomodal particle size distributions were observed for microfluidized double emulsions and those prepared by rotor stator homogenization treatment, respectively. The inclusion of xanthan gum decreased the size of the oil droplets, which resulted from the decreased viscosity ratio between the oil and the aqueous phase. Also, an increased homogenization intensity induced a decreased droplet size, resulting from the higher shear stress applied to the fluid. The entrapped water volume fraction was about 90% for all double emulsions prepared with rotor stator homogenization treatment and without xanthan gum. As the cream and serum layers of the double emulsions stabilized with xanthan gum were not separated during 2 hours of analytical centrifugation, the reliable estimation of the enclosed water volume fraction was troublesome. The release rate of L-leucine in double emulsions prepared with rotor stator homogenization treatment was proportional with the homogenization level, which can be explained from the smaller droplet size: a faster release rate was observed at higher homogenization intensity as a result of a smaller droplet size. Xanthan gum addition remarkably increased the release rate of L-leucine, which was thought to be due to the smaller droplet size. Preliminary gastrointestinal tests indicated that double emulsion encapsulation provided a gradual release of amino acids in the gastrointestinal environment (section 4.10). The release of amino acids might be governed by diffusion in the gastric environment, whereas the oil digestion can change this mechanism as well as the relase rate. The smaller droplets obtained after intestinal digestion was likely due to the triglycerides hydrolysis which resulted in the disruption of the oil phase and hence release of encapsulated amino acid. In section 4.11, the release of L-phenylalanine was investigated by means of high resolution NMR diffusometry. As the first and last decay profile of water overlapped, it follows that the enclosed water volume fraction remained constant during incubation (at 30 and 50 °C). Moreover, a slower amino acid diffusion coefficient was obtained in the external water phase as compared to the internal water phase (i.e. before emulsification). This might be due to the presence of xanthan gum in the external (but not in the internal) water phase, which restricts the thermal motion of the amino acids, and hence the diffusion behaviour. The diffusion behaviour of L-phenylalanine in double emulsions exhibited a typical bi-exponential decay, which enabled to discriminate between encapsulated (slowly diffusing due to restriction in a spherical confinement) and released (fast diffusing due to the absence of confinements) amino acid. Whereas the main purpose of the experiment was to enable a more detailed investigation of the influence of the incubation temperature, a clear conclusion was hampered by the extensive release before the start of the NMR experiment. This research enables a better insight to understand the influence of molecular properties and double emulsion composition on the release kinetics. From a practical point of view, our results provide guidance in the design of colloidal systems for the encapsulation and controlled release for nutritional applications. In order to extend this study, the double emulsions containing amino acids can be incorporated in the food matrix or drugs.
Effects of novel food processing techniques on bioaccessibility and transepithelial transport of cranberrybush polyphenols

(Graduate School, 2021-08-06) Özkan, Gülay ; Çapanoğlu Güven, Esra ; 506142507 ; Food Engineering

Phenolic compounds, which are present in a wide variety of foods such as fruits, vegetables, flowers and leaf of plants, exhibit a variety of beneficial effects including antimicrobial, antioxidant, antidiabetic, diuretic, hypoglycemic, cough reliever, antiinflammatory and antiviral activities as well as prevention of cardiovascular, pancreas, liver and kidney diseases. However, most of the polyphenols have poor water solubility, chemical instability in gastrointestinal tract and, thus, a reduced bioavailability. Therefore, a wide variety of attempts have been investigated to improve the solubility, stability, bioaccessibility and bioavailability of phenolic compounds. Considering the above, a research framework to study the effects of novel processing techniques on the antioxidant capacity, bioaccessibility and bioavailability of cranberrybush polyphenols has been developed. The objectives of this Ph.D. thesis were (i) to determine the effects of novel non-thermal food processing on cranberrybush polyphenols and vitamin C; (ii) to investigate the effects of non-thermal food processing and food matrix on bioaccessibility and transepithelial transportation of bioactive compounds, in particular chlorogenic acid, from cranberrybush (Viburnum opulus) using combined in vitro gastrointestinal digestion/Caco-2 cell culture model; (iii) to obtain an effective Supercritical Anti-Solvent (SAS) coprecipitation of quercetin or rutin with polyvinylpyrrolidone (PVP), enhancing the dissolution rate, and, therefore, improving the bioavailability of these natural antioxidant compounds; (iv) to determine the effects of SAS processing and food models on the antioxidant capacity, bioaccessibility and transport dynamics of flavonol-loaded microparticles by using combined in vitro gastrointestinal digestion/Caco-2 cell culture model. To achieve these goals, four different experiments (Chapters 3-6) were conducted. Firstly, effects of high pressure processing (HPP) and pulsed electric field (PEF) treatments on physicochemical properties, bioactive compounds, antioxidant capacities and polyphenol oxidase activities of cranberrybush purée samples were evaluated (Chapter 3). Following that, non-thermal treated cranberrybush purée samples as well as cranberrybush juice/water, bovine or almond milk blends were subjected to combined in vitro gastrointestinal digestion/Caco-2 cell culture (Chapter 4). In line with the outcomes of previous chapter, in order to increase the bioavailability of some phenolic compounds that could not be absorbed across the gut epithelium after transport experiments with cranberrybush samples, the micronization of two flavonoids, quercetin and rutin, and their coprecipitation with PVP were studied by using SAS processing to increase their solubility and enhance their stability during gastrointestinal tract (Chapter 5). Finally, SAS-processed flavonoids in different simulated food models were exposed to combined in vitro gastrointestinal digestion/Caco-2 cell culture in order to investigate their transport dynamics (Chapter 6). In Chapter 1, research framework and objectives of this Ph.D. thesis are introduced. Following that, in Chapter 2, comprehensive reviews on the antioxidant properties, bioaccessibility and bioavailability of polyphenols are presented, with a specific focus on the application of novel processing techniques. Initially, a critical evaluation of the effects of novel non-thermal food processing technologies on the beverage antioxidants have been provided. Then, the studies about microencapsulation methods for food antioxidants regarding principles, advantages, drawbacks and applications have been reviewed. Afterwards, effects of encapsulation on the bioaccessibility and bioavailability of phenolic compounds were discussed. Lastly, in vitro and in vivo approaches on interactions of phenolics with food matrix were described. In Chapter 3, the effects of high pressure processing (HPP; 200-600 MPa for 5 or 15 min) and pulsed electric field treatment (PEF; 3 kV/cm, 5-15 kJ/kg) on physicochemical properties (conductivity, pH and total soluble solids content), bioactive compounds (vitamin C, total phenolic, total flavonoid, total anthocyanin and chlorogenic acid contents), antioxidant capacities (DPPH and CUPRAC assays) and polyphenol oxidase activity of cranberrybush purée samples were evaluated. Results showed that conductivity increased significantly after PEF (15 kJ/kg) treatment. PEF and HPP treatments resulted with a better retention of bioactive compounds (increase in the total phenolic content in the range of ~4 – 11% and ~10 – 14% and total flavonoid content in the range of ~1 – 5% and ~6 – 8% after HPP and PEF, respectively) and antioxidant capacity compared to untreated sample. HPP reduced residual enzyme activity of PPO comparatively better than PEF. Besides, cranberrybush polyphenols were identified along with their detected accurate mass, molecular formula, error in ppm (between the mass found and the accurate mass < 10 ppm) of each phytochemical, as well as the MS/MS fragment ions. UPLC–QTOF–MS/MS analysis of cranberrybush led to the identification of flavan-3-ols (catechin, epicatechin, epi(catechin) hexoside), proanthocyanidins (procyanidin dimer, procyanidin trimer, procyanidin dimer monoglycoside), flavonols (quercetin, quercetin-deoxyhexose, quercetin-3-O-glucoside, quercetin pentoside hexoside, rutin, isorhamnetin-3-O-rutinoside), flavone (diosmetin-rhamnosylglucoside), phenolic acids (caffeic acid, chlorogenic acid, coumaric acid, p-coumaroyl-quinic acid) as well as anthocyanins (cyanidin-3-glucoside, cyanidin-3-rutinoside and cyanidin-3-xylosyl-rutinoside). In conclusion, high retention of bioactive compounds was achieved, with a potential extraction of vitamin C, phenolics, flavonoids and anthocyanins in cranberrybush purées after HPP and PEF treatments at selected processing intensities. In Chapter 4, effects of food matrix and non-thermal food processing on bioaccessibility and transport dynamics of cranberrybush phenolics, in particular chlorogenic acid, in a combined in vitro gastrointestinal digestion/Caco-2 cell culture model were studied. Results showed that PEF treatment at 15 kJ/kg specific energy input resulted in a higher recovery of total flavonoid content (TFC; increase of 3.9% ± 1.1%, p < 0.0001), chlorogenic acid content (increase of 29.9% ± 5.9%, p < 0.001) and antioxidant capacity after gastrointestinal digestion. The present study also demonstrates that untreated and treated samples display comparable transport across the epithelial cell layer. Besides, addition of milk matrix have a positive effect on the stability and transportation of chlorogenic acid. JM increased the transport efficiency of chlorogenic acid by 3.5% ± 0.8% (p < 0.0001), while JA increased the transport of chlorogenic acid by 3.3% ± 0.5% (p < 0.001) in comparison with JW blend. The in vitro gastrointestinal digestion/Caco-2 cell culture method applied in this chapter was used in the succeeding chapter (Chapter 6). In Chapter 5, micronization of two flavonoids, quercetin and rutin, and their coprecipitation with polyvinylpyrrolidone were studied by using the SAS process. In particular, optimum conditions in terms of operating pressure, type of the solvent, total solute concentration and polymer/active ratio for the formation of spherical composite microparticles were determined. Morphology, mean size and size distribution of the particles were analyzed and discussed. The effectiveness of the process was also verified through entrapment efficiency and dissolution tests. Overall, amorphous microparticles were produced with total solute concentrations greater than 20 mg/mL. Furthermore, release studies confirmed the improvement of the flavonoids dissolution rates: 10 and 3.19 times faster dissolution rates were achieved with PVP/quercetin and PVP/rutin microparticles rather than those of unprocessed quercetin and rutin, respectively. Besides, the high entrapment efficiencies, up to 99.8%, were achieved for quercetin and rutin coprecipitates by using DMSO, which was the solvent chosen to coprecipitate the flavonoid compounds with PVP by the SAS process. Consequently, the characteristics of the powders could allow to use of these quercetin and rutin loaded microparticles in pharmaceutical and nutraceutical applications due to their high antioxidant and anticancer benefits for, in which the flavonoid compounds have high stability and bioavailability. In Chapter 6, effects of SAS processing on bioaccessibility and transepithelial transportation of quercetin and rutin were investigated by using a recognized combined gastrointestinal digestion/cell-based assay. Moreover, aqueous hydrophilic and acidic conditions were simulated to analyze food-related factors that could have an impact on the transport of these compounds across the gut epithelium. SAS processing improved the recovery of the quercetin (94 and 13 times in hydrophilic and acidic conditions, respectively) and rutin (7 and 2 times in hydrophilic and acidic conditions, respectively) after in vitro digestion. Besides, transepithelial transportation of PVP/quercetin and PVP/rutin microparticles were found to be much higher rather than unprocessed quercetin and rutin. Finally, in Chapter 7, based on the outcomes of the previous chapters, the general discussions and conclusions on the antioxidant properties, bioaccessibility and bioavailability of polyphenols were presented. The status and main outcomes of this thesis were discussed under the headings of fate of the polyphenols after application of novel non-thermal food processing techniques, effects of encapsulation on the food phenolics and interactions of phenolics and food matrix. During the discussion on the effects of encapsulation on the food phenolics, important factors to be considered during encapsulation, advantages and drawbacks of these techniques, their impacts on the antioxidant properties, bioaccessibility and bioavailability of phenolic substances were discussed. Besides, while referring to the interactions with food matrix, special attention has been paid to comparison of the different in vitro and in vivo digestion models.
Formation of anthocyanin-rich black carrot extract loaded potato protein particles by ternary compressed CO2-ethanol-water mixture extraction and PGSS-drying

(Graduate School, 2021-08-16) Düzgün Yavuz, Merve ; Özçelik, Beraat ; 506142501 ; Food Engineering

Black carrot anthocyanins have importance for food industry as it is a natural colorant and possesses health beneficial effects regarding the functional food and beverages. Anthocyanins are conventionally extracted by using organic solvents such as methanol, acetone or water with small amount of hydrochloric acid or formic acid. These methods are problematic due to the residues of organic solvents remaining in extracts that are associated with food safety or due to the degradation of anthocyanins at high temperatures which required for acidified water extraction. Due to these problems, it is crucial to develop novel methods which are environmentally sustainable and efficient, resulting in high yields. The extraction using sub- and supercritical carbon dioxide (sc-CO2) has been growing as an alternative to conventional extraction, as it can potentially fulfill these demands. The anthocyanin- rich extracts are still very labile to different environmental conditions. Encapsulation or complexation with different biopolymers of bioactive compounds provides a good solution before the incorporation of these valuable compounds in food and beverages. Complex coacervation is one of the encapsulation methods which finds a widespread relevance in functional biomaterials consisting the food and beverage area. It is a physicochemical process that be conducted at mild temperatures without high pressures. The other process applied in this thesis for the purpose of complexation was Particles from Gas saturated Solutions–Drying.
Emerging approaches for non-thermal modification of proteins isolated from de-oiled sunflower cake

(Graduate School, 2021-09-10) Gültekin Subaşı, Büşra ; Çağanoğlu Güven, Esra ; 506172506 ; Food Engineering

When considered their biological accessibilities, animal-based proteins are known to be closer to the concept of "complete protein" rather than that of plant-based proteins with their higher bioavailabilities. However, increment of world population, damaging of natural sources due to false agricultural policies and climate crisis, high carbon release ratios during their production, high potential for extreme consumption and pollution of water sources, animal welfare issues, religion/ethnic concerns, expansion of diet styles and philosophies like veganism/vegetarianism are all some of the major reasons of community, industry, and food scientists' increased attention about sustainable plant-based proteins in order to replace animal proteins, day by day. Along with their nutritional importance, due to owning the techno-functional properties such as foaming, film/gel-forming, and emulsification, proteins had extensive application areas in the food industry. Recent studies concerning the sustainable plant-based protein sources mainly focused on protein extraction or recovery that have functional properties from plant wastes and/or by-products. Discovery of novel plant proteins with high or improvable techno-functionalities is of extreme importance due to being used as the replacers of animal-based proteins, urgently. For this purpose, sunflower is one of the most studied plants as a protein source coming after the soy, which is the heading plant for this area in the world. Due to having a high protein content, including no allergenic or toxicologic concerns enable the sunflower press cake, which is the oil extraction by-product, more attractive for the mentioned purposes. Under the lights of these explanations, research was planned to frame the characterization and investigating the techno-functional properties of proteins that will be extracted from industrially de-oiled sunflower cake. The objectives of this Ph.D. thesis was (i) isolation and characterization of proteins from de-oiled sunflower cake; (ii) developing a novel non-thermal treatment approach aiming to change the structural properties of protein isolate; (iii) proposing a novel non-thermal treatment perspective using a well-known thermal method aiming to change the structural properties with the purpose of improving its functionality (iv) and investigating the effect of this proposed method on sunflower protein emulsification property in detail. Four different experimental studies (Chapters 3-6) were conducted in order to fulfill the declared purposes. Initially, protein isolates were extracted from de-oiled sunflower cake, characterized and its functional properties were evaluated from a wide-angle perspective (Chapter 3). Then the protein was exposed to a developed nonthermal "moderate electric field treatment" against a reference protein and their structural differences were assessed (Chapter 4). Based on obtained data from the previous chapter, another novel approach, "non-thermal electromagnetic field treatment" was proposed and applied on dry powder protein thereafter the structural alterations of protein were discussed (Chapter 5). Emulsification properties of proteins that were treated with non-thermal electromagnetic field were examined extensively (Chapter 6). In Chapter 1, the main goals and the scope of this present Ph.D. thesis are defined. Right after in Chapter 2, a review study that comprehensively covering the techno-functional properties and potential modification methods of sunflower protein are presented. Initially, compositions of studied sunflower proteins with their quantitative content ranges were reported. Following that, the ways of how de-oiled press cake and isolated sunflower protein were applied in real food systems have been reviewed. Afterwards, the varying methods for protein extraction, isolation of phenolic compounds, and recovery for removed phenolics were assessed. As the last but is the focal point of this review was examining all defined and studied functional properties of sunflower protein up to date, and the modification methods that were used to improve them. In Chapter 3, both types of protein isolated were extracted from sunflower cake; as it is in natural form with phenolic compounds and as de-phenolized isolates. Natural phenolic compounds (dominantly chlorogenic and caffeic acids) that exist in the press cake make complexes with protein molecules and are isolated as adjoints to the structure. In this part, the effect of these natural phenolic compounds on protein content, color, amino acid and mineral compositions, protein surface structure, protein secondary structure, thermal properties, ζ-potential, foaming and the viscoelastic properties at the air/water interface were investigated. According to the proximate composition analysis, it was observed that the moisture and the crude protein ratios increased around 59 and 9%, respectively while the ash content decreased 53% when the phenolic compounds were achieved to be removed at 98%. The color of dephenolized protein was visibly changed from dark green to light brown, the protein surface was observed as roughened and porous rather than natural protein isolate. Isoelectric points were calculated as pH. 4.37 and 4.82 for natural and de-phenolized sunflower proteins, respectively. After the removal of phenolic compounds, significant decreases for all minerals were observed except for Se and Sr. No significant changes were obtained for protein secondary structure and thermal properties however, its hydrophobicity increased when de-phenolized. The most substantial differences were observed for foam stability and interfacial properties of de-phenolized protein at the air/water interface and it was reported that functional properties significantly improved after removal of phenolic compounds. Based on the results of this study, de-phenolized sunflower protein isolate was used as the only material for the following studies (Chapters 4-6). During industrial oil processing, using high treatment temperatures for high production efficiencies coupled with applied mechanical forces induce the globular sunflower protein, helianthinin (11S:2S with a ratio of 7:3) to build more compact globules and gain a kind of heat resistance. According to the literature, in order to unfold this "already denaturized" sunflower protein to improve its functional properties, a heat treatment over 90 °C should be applied. Due to the fact that, within the scope of this Ph.D. thesis, a novel "non-thermal moderate electric field treatment" was developed and applied on sunflower proteins. In Chapter 4, sunflower protein was exposed to an electric field with varying voltages for different times below the 45 °C. Since it was the first application of this proposed technique, sodium caseinate, as a widely used and known reference protein, was exposed to the same processing conditions aiming a better understanding for the effects of non-thermal moderate electric field. Proteins were examined in terms of both structural and functional properties after processing. Smaller average particle size, lower interfacial tension at the air/water interface as well as changed secondary and tertiary structures besides different thermal properties were observed. Sunflower protein was successfully unfolded with the proposed method, non-thermally. In Chapter 5, due to the very same reasons and motivations about the unfolding of heat-resistant sunflower protein, another novel, and non-thermal approach was proposed and applied. Microwave treatment as one of the most widely known electromagnetic radiation applications is a thermal processing method however it also has a simultaneous non-thermal effect on samples during processing, whose exact mechanism is still unclear. Due to allowing for processing the sample on "dry basis", it was assumed that the polar amino acids in the protein structure will absorb the electromagnetic energy, enables rotating around the central carbon atom and/or forming free radicals and consequently, inducing the structural changes such as partial unfolding and/or refolding. After processing it was observed that, the polar amino acid ratio of processed protein was changed, particle size decreased, protein's secondary and tertiary structures altered, thermal stability decreased and thermogravimetric losses were obtained. This second proposed non-thermal novel treatment succeeded to induce the sunflower protein for partial unfolding. Following the exposure of sunflower proteins to non-thermal electromagnetic field and observing promising structural alterations, a functional property was decided on and examined in detail in Chapter 6, instead of a general overview covering multiple functional properties. Electromagnetic field application increased the protein solubility and surface hydrophobicity besides more homogenous and stable (1.43 fold) emulsions with smaller droplet size were obtained. Similarly, in that of Chapter 4, sodium caseinate was used as a reference protein and exposed the same treatments to compare particularly emulsification properties. Despite the higher surface tensions at the oil/water interface were observed for sunflower protein samples rather than sodium caseinate, more elastic but less stretchable solid-like protein layers were determined at the interface. Consequently, the proposed application fulfilled the aim of altering the structure of sunflower protein and having the potential to improve its functional properties. Finally, in Chapter 7, based on the data obtained from the previous parts a comprehensive discussion and results about the changing the structure of sunflower protein using proposed novel treatment approaches and their potentials to improve protein's techno-functional properties are presented. Advises for future researches are also provided. The results observed from this Ph.D. thesis were examined under the titles of characterization of sunflower protein, the effect of natural phenolic compounds on protein structure and functional properties, the effect of non-thermal moderate electric field application on protein structure, the effect of non-thermal electromagnetic field application on protein structure and functional properties. Foaming and emulsification were chosen as the functional properties to investigate however, possibilities to change the protein structure were predominantly focused on throughout the whole study.
Improvement of functional properties of chickpea flour and application in bakery products

(Lisansüstü Eğitim Enstitüsü, 2022) Nazari, Parnia ; Karaça, Aslı Can ; 741152 ; Gıda Mühendisliği Bilim Dalı

Nohut unu, besleyici ve fonksiyonel özellikleri ile ön plana çıkan ve yeni ürün formülasyonlarında sıkça kullanılmaya başlanan bir gıda bileşenidir. Bu araştırmanın amacı, kavurma ve ultrason işlemlerinin nohut ununun fonksiyonel özellikleri üzerindeki etkilerini araştırmaktır. Emülsiyon ve köpük oluşturma ve stabilize etme özelliklere özel önem verilmiştir. İlk çalışmada, numuneler önceden 80, 90, 100, 110 ve 120 °C'ye ısıtılmış bir fırında 1 dakika süre ile kavrulmuştur. Daha sonra fizikokimyasal ve fonksiyonel özellikler incelenmiştir. Her numunede kavurma işlemi ile kütle yoğunluğunun önemli ölçüde arttığı bulunmuştur. Kavurma işlemi sonrasında renk parametreleri, emülsiyon aktivitesi ve stabilitesi, köpürme ve termal özellikler arasında anlamlı farklar tespit edilmiştir. İkinci çalışmada 100°C ve 120°C'de 2,5, 5, 7,5 ve 10 dakikalık farklı sürelerde kavurma incelenmiştir. Sonuçlar, suda çözünürlük indeksinin önemli ölçüde arttığını, kırmızılık ve sarılık değerlerinde farklılık olduğunu göstermiştir. Numunelerin emülsiyon, köpürme ve termal özellikleri, kavurma süresi ve sıcaklığına göre değişimi göstermiştir. Sonuç olarak, 100℃'de 2,5 dakika kavrulmuş numunenin özelliklerinin en iyi olduğu gözlenmiştir. Son olarak, farklı süreler için farklı amplitüd değerlerinde ultrason işleminin köpük oluşturma ve emülsiyon özellikleri üzerindeki etkileri araştırılmış ve bu faktörlerin hiçbirinin anlamlı ölçüde etkilenmediği bulunmuştur. Son olarak, en uygun koşullarda kavurma işlemi uygulanmış nohut unu fırıncılık ürünlerinde kullanılarak ürünün duyusal özellikleri üzerindeki etkisi incelenmiştir. Duyusal değerlendirmeleri incelemek için uygulama olarak bir çeşit nohut kurabiyesi hazırlanmıştır. Toplam 20 kişi tarafından değerlendirilen duyusal panellere dayanarak, kontrol numunesinin tadı ve dokusuna göre, genel olarak 90 ve 100°C'de kavrulmuş unun kullanıldığı numuneler daha iyi sonuç verdi. 100°C'de 2,5 dakika kavrulmuş numunede sonradan oluşan tat (fasulye/yeşil tat) önemli ölçüde azaldı. Sonuç olarak, incelenen özellikler ve duyusal değerlendirmeler göz önüne alındığında, fırıncılık kullanımı için en uygun örneğin 100℃'de 2,5 dakika kavrulmuş un örneği olduğu görülmüştür. Kavurma işlemi ile nohut ununun fonksiyonel ve duyusal özelliklerini iyileştirilmesinde kullanılabilir.
Development of pea protein agar based biodegradable film with the incorporation of essential oils

(Graduate School, 2022) Ozhan, Selin ; Yeşilçubuk Şahin, Neşe ; Saygun, Ayşe ; 725922 ; Food Engineering Programme

In recent years, there is an increased awareness of sustainability in the world. People are looking for more sustainable solutions in packaging the industry since it is seen as one of the most polluting agents in the environment. Edible films and coatings are alternatives to reduce plastic packaging usage in the food industry. While it has an advantage for being sustainable, it also provides a good barrier, sensory, and quality properties in the foods. This study aimed to investigate the characterization of pea protein and agar edible film and then add essential oils to increase the antimicrobial effect of the edible film. For this purpose, 4 different essential oils are used; eucalyptus, thyme, lemon and niaouli in 1%, 2%, 3%, 4% and 5% (v/v) concentrations. Edible films are produced by using the solvent casting method. As the first step of this study, different film-forming materials were investigated and prepared in the laboratory to observe their edible film-forming capability. According to the results, pea protein and agar were chosen as the main edible film materials because they can form flexible and transparent films. Furthermore, essential oils were researched in the literature. The proper essential oil combination with edible films and the concentration were investigated. Thyme, eucalyptus, niaouli, and lemon oil were chosen because of their high antimicrobial activities and being capable to incorporate with edible films. After the decision of main materials, the pea protein and agar films were produced and thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) was checked to understand the characterization of the main film. After the addition of essential oils, swelling analysis, antimicrobial activity, and color analysis were done. TGA indicates the weight decrease of the film due to the water, volatiles, and plasticizer losses during the analysis. In DSC analysis, the Tg value is observed as 73℃. Since the pea protein and agar film seems flexible structure at room temperature, having a higher Tg value than room temperature may show that it is not mechanically strong for processing and it will be in more rubbery and softer structure at the higher temperatures. Lastly, DMA analysis was unsuccessful due to the weak mechanical strength of the film. After essential oils addition to pea protein based film, antimicrobial activities of essential oil incorporated edible films were analyzed. Based on the results, swelling and color analysis were conducted for the films that showed antimicrobial effect and also 5% oil concentration. For antimicrobial analysis, the agar disc diffusion method was used and essential oil incorporated film's antimicrobial activity was investigated against Escherichia coli, Staphylococcus aureus, and Aspergillus niger. According to the results, 1% addition of essential oil to the edible film did not show any antimicrobial effect against any of the microorganisms. In 2% essential oil addition, thyme and niaouli oil started to show antimicrobial effects against gram (+) and Gram (-) bacteria. After 3% addition of thyme oil, antimicrobial effects were observed against both bacteria and fungus. In bacteria, there is no direct correlation between the concentration of essential oil and the antimicrobial zones in the Petri dishes. The largest zone which was 2.7 cm observed against E. coli is 3% thyme oil incorporated edible film, and the largest zone against S. aureus is from all 3%, 4%, and 5% thyme oil that all give 2.3 cm in one of the analysis. On the other hand, there was a direct correlation between the concentration of essential oil and the antimicrobial activity against fungus. In 5% thyme oil incorporated film, there was almost no growth in the Petri dishes however the growth of the fungus increases as the concentration of thyme oil decreases. Additionally, swelling analysis was conducted for 5% essential oil incorporated films and 2% niaouli, 2% thyme, 3% thyme, and 4% thyme incorporated films that show antimicrobial effects against bacteria. It is found that 5 ml thyme oil is the least absorbent one in the both water and saline water environment. In a saline water environment, it started to lose its weight from the first hour. Hence, it can be said that it is not suitable for salted food application or any salty environment. On the other hand, 2 ml niaouli oil incorporated edible film is seen as the most absorbent one in both environments. During the analysis, all edible films show some peaks in different time zones. The reason can depend on the oil concentrations and hydrophobicity rates. In terms of color analysis, the same samples were used for swelling analysis. According to the average of six repetitive measurements, 2 ml niaouli oil incorporated edible film gives the least yellowish color, and the 4 ml thyme oil incorporation of the film gives the most yellowish. The results are evaluated by using the b* parameter which provides the rate of yellow color on the materials. In conclusion, this study shows that pea protein and agar can yield an edible film, and when incorporates with the proper amount of thyme oil, it can show antimicrobial activity against gram-positive and gram-negative bacteria and fungus.
Encapsulation of oil-based cheese aroma by using spray-drying and efficience of microcapsules in model foods

(Graduate School, 2022) Ertan Tütüncü, Sena ; Özçelik, Beraat ; Özgüven, Mine ; 737832 ; Food Engineering Programme

Since the world has existed, food consumption has been critical for the continuation of life. Appearance, flavor, and taste play an important role in the preference of foods in nature. In modern times, these parameters have been controlled and improved. Fermentation is invented to increase the shelf-life of the food; in addition, new volatile compounds are formed during the fermentation process. Cheese is the most consuming fermented product, and different types of cheese are made by changing fermentation and process parameters. These parameters also affect the odor and taste, providing the uniqueness of cheese. Each volatile compound has a special odor and taste, therefore, containing various volatile compounds allows different cheese varieties to have their unique odor and taste. Various extraction techniques are distillation, static headspace, dynamic headspace, solid-phase microextraction (SPME), stir bar sorption extraction, and vacuum distillation applies for the extraction of the cheese volatile compounds. Depending on the volatile compounds' qualifications such as the sensitivity of heat, light, and temperature; appropriate extractions should be chosen. The encapsulation process prevents flavors from being affected by adverse environmental conditions. Various techniques are used to encapsulate the active material. Selecting the suitable encapsulation method depends on the core material release features, wall material properties, project cost, and aim. Preparation of emulsion is the first and fundamental step of encapsulation. Wall materials that cover the core material may be consists of carbohydrates, protein, or other materials. Starch, gum, and maltodextrin carbohydrate-based derivatives to use in encapsulation; however, for getting more encapsulation efficiency carbohydrate and protein-based materials are preferred together. Both animal and plant-based derivatives are used as protein wall materials. High pressure, micrtechniquesing technique, and ultrasonication are used to homogenize and provide emulsion to good dispersion. The spray drying technique is one of the most common encapsulation techniques in the food industry. The spray drying process is based on the principle of atomizing the material to be dried under high pressure and then drying it in a very short time with hot dry air. In this experiment, commercial cheese aroma is encapsulated by the spray drying technique. Using maltodextrin and protein are used as wall material at different concentrations. 30 % of the emulsion mixture consists of solid ingredients. This solid content is prepared with 16 % aroma and 84 % mixture of maltodextrin with dextrose equivalent 11-16 and whey protein concentrate, 50 %. Protein content in the solid mixtures is 8 % and 4%. These emulsions are kept in a shaking bath at 40 C° for 20 hours at 80 rpm to improve hydration. 16 % aroma of total emulsion is added to both emulsions. After the hydration and adding aroma, the emulsion is mixed first at 450 rpm, for 1 hour; then homogenized by Ultra-turrax at 17000 rpm for 5 minutes. Laboratory scale Buchi B-290 is used at an 8 mL/min feed rate, 180 ± 2 C° inlets, and 80 ± 2 C° outlet temperature. Encapsulation duration keeps 40 minutes. Encapsulated and commercial aroma is added, a total of 1 % flavor, in cracker dough samples that include 60 % flour, 15 % oil, and other ingredients. Then the crackers are cooked in the oven at 220 C°, for 10 minutes. The aroma added cracker is oiled at % 10 without aroma. Cracker dough without aroma is prepared and cooked; however, the encapsulated aroma and liquid aroma are added in the oil process at 0.2 %. GC & MS analysis results are compared with the results of commercial liquid flavoring as a reference. Encapsulated A and B aroma volatile compounds concentrations show similar results. Butyric acid is lost after the encapsulation process; however, 9,12-Octadecadienoic acid (Z, Z) concentration dramatically increases after the encapsulation in both encapsulated aromas. 2-Decenal and 2-Nonenal concentrations show a slight rise and these compounds are also derivatives of the oxidation. Heptanoic and Undecanal concentrations in the encapsulated aroma are higher than in the liquid flavor. Other compound concentrations are similar between A & B aromas and commercial products. Added the encapsulated aromas and commercial aroma in cracker doughs, volatile compounds concentrations do not show dramatically difference; however, 2- Decenal concentration in three samples slightly increases with comparing the reference liquid aroma. 9,12-Octadecadienoic acid concentration is differentiated between encapsulated aroma and liquid aroma, higher concentration in the encapsulated aroma. Heptanoic acid concentration could not be maintained in doughs when using liquid flavoring and showed a decrease. After the cooking, adding the aroma to the top oil process demonstrates the different volatile compounds concentrations. Heptanoic acid, 2-Nonenal, 2-Decenal, dihydro-5-pentyl-2(3H)-Furanone, and Tetradecanal compounds concentrations are higher than reference liquid aroma and cracker that include aromas in the dough. Other compounds' concentrations are similar to the commercial aroma. The change in the concentrations of the volatile components in the aroma may be caused by oxidation and the combination of the aroma with other components and creating different reactions. The panelists do not realize dramatically difference between using encapsulated B aroma and liquid aroma in dough with cheese odor, cheese flavor, aftertaste of cheese flavor, and general taste. Significant differences are observed between crackers that use oil including aroma and added commercial aroma in the oil process. The samples using the encapsulated B flavor in the oil are more like in terms of cheese odor and flavor, aftertaste cheese flavor, and general taste than the crackers using the reference aroma. In line with these results, industrial cheese flavor managed to preserve most of its volatile components with its wall material consisting of maltodextrin and whey protein concentration. The encapsulated aromas are used in the dough of cracker samples, which are applied at high temperatures during cooking, and in the oil applied to them after cooking. Although some volatile compounds of crackers, such as butyric acid and 2-nonenal, are lost when high temperature is applied; a high amount of volatile components are retained. Added aroma in oil shows greater volatile compound concentrations, also added encapsulated aroma in oil is more preferred than others.
Bioactivity and functionality of chickpea protein-spent coffee phenolic complex

(Graduate School, 2022) Vafa, Hamedreza ; Şeker, Dursun Zafer ; Food Engineering Programme

The demand for alternative protein resources is growing by the day, due to factors such as rising population and changing environmental conditions. Plant-based proteins are one of the most beneficial protein sources to consider in this regard. However, since the functional and nutritional properties of plant-based proteins are inadequate to those of animal-based proteins, several modification applications are being explored in order to improve these properties. Protein interaction is one of the promising protein modification methods that have the potential to improve the bioactive properties of plant-protein resources. The interaction of chickpea protein with spent coffee phenolics was investigated in this study under two conditions interaction conditions including pH 7 and pH 9. The binding properties, the effect of the interaction on the structure and functional properties of the chickpea protein and the in vitro bioaccessibility properties of the complex were then investigated to characterize the effect of interaction on protein and phenolic compounds. Although chlorogenic acid was found in the extract, it was not found in the protein phenolic solution. Besides that, the amount of catechin in the protein phenolic interaction solution was lower than in the phenolic extract. Therefore, it was concluded that these two compounds were bound with chickpea protein. The effect of protein phenolic interaction on the functional properties of chickpea protein was investigated regarding protein solubility, foaming and emulsifying properties. There was no significant difference on the solubility of chickpea protein after its interaction with phenolic compounds. Similarly, there was no significant difference between foaming properties and emulsion capacity and stability of chickpea protein after at pH 7 (p>0.05). However, these properties of chickpea protein are enhanced at pH 9. The foaming capacity of chickpea protein was 43.33%, while the phenolic addition ranged from 123.33 to 142.89% with no significant difference between concentrations. Similarly, interaction at pH 9 increased the emulsion capacity and stability of chickpea protein by 10% and 8%, respectively. The emulsion activity index and stability index of the samples increased after both interactions. The CPI + PE 1 example showed the highest increase in chickpea protein. The determined increase was 55 % for the interaction at pH 9 and 47% for the interaction at pH 7, respectively. In the same examples, the emulsion stability indexes increased by 70% and 6%, respectively. In vitro bioavailability analysis was performed to examine the bioactive properties of protein phenolic solution and its stability during gastrointestinal digestion. The total phenolic content and antioxidant capacity of the samples were increased with the addition of phenolic extract. After intestinal digestion, the total phenolic content in covalent samples decreased, however, no statistically significant difference was observed after the interaction at pH 7. The total phenolic content of the samples interacted at pH 9 decreased after intestinal digestion, but there was no statistically significant difference the samples interacted at pH 7. The ABTS method indicated that, while total antioxidant capacity was reduced in the gastric phase, total antioxidant capacity was increased by up to 33% only after the interaction at pH 9 in the intestinal phase. Although there was little or no increase in total antioxidant capacity of the samples in the gastric phase, an increase in antioxidant capacity of up to 68 and 18 %, respectively, was observed in the intestinal phase after interaction at pH 7 and pH 9 with the addition of phenolic. Zeta potential, FTIR spectrum, and fluorescence intensity analyses were used to investigate the effect of the interaction on the structural properties of the chickpea protein. While the samples' absolute zeta potential was low after interaction at pH 9, the absolute zeta potential increased after interaction at pH 7. The FTIR spectrum of the analysis showed that there was a change in the secondary structure of the chickpea protein due to the change in the amide bands. Also, change in the tertiary structure was detected due to the change in the fluorescence intensity after both interaction conditions. Consequently, spent coffee ground phenolics were found to cause changes in protein structure as a result of interaction with chickpea protein. The functional properties of the chickpea protein have been improved as a result of these changes. It was concluded that phenolics from spent coffee grounds could be an effective alternative protein modification for chickpea protein.
Encapsulation of cumin seed oil in chickpea protein- maltodextrin matrix

(Graduate School, 2022-02-14) Atlı, Onur ; Karaça, Aslı Can ; 506181509 ; Food Engineering

This study aimed to investigate developing a plant-based protein matrix for microencapsulation of cumin oil, by determining optimum pH for solubility, emulsion stability of chickpea protein isolate (CPI) and investigating the effect of the matrix composition on encapsulation effiency and aromatic composition of cumin oil. Solubility, net surface charge, and emulsifying properties (emulsion activity/stability indices, and creaming stability) of CPI at ranging pH 3.0-9.0 were investigated. The highest protein solubility (94.4%) and emulsion activity index (61.8 m2/g), and the highest creaming stability (9.8% separation) was obtained at pH 9.0. CPI stabilized emulsions were optimized based on pH due to the higher emulsion stability index, which is 123.8 min at pH 7.0. CPI concentration of 0.5-2.31% (w/w) and oil concentration of 5-23.11% were adjusted in order to investigate the emulsion stabilization capacity of CPI using response surface methodology. It was observed that obtained CPI has the lowest effect on emulsion formation. Optimum conditions for minimum creaming were identified as: 0.19% CPI concentration and 6.83% oil concentration. CPI was found to be thermally stable with high denaturation temperature (161.4°C) and required 142.2 J/g enthalpy for denaturation. Cumin (Cuminum cyminum L.) seed essential oil was microencapsulated employing the complex matrix formation of CPI and maltodextrin DE 12-16 using spray drying. Effects of cumin oil concentration (10-20%), CPI concentration (1-3%) and maltodextrin (MD) concentration (25-35%) on the physicochemical characteristics and aromatic composition of the microcapsuled cumin oil were investigated. It was observed that, CPI-MD complex matrices had positive effects on microencapsule properties such as relatively lower surface oil, and higher encapsulation efficiency and oil retention, when they were formulated properly. Oil retention of 86.6–96.4%, encapsulation efficiency of 90.9–98.4%, and surface oil of 1.4–7.9% were obtained in samples. Correspondingly, it was observed that MD–CPI interaction was an effective parameter for emulsion stability. Optimum conditions for maximized oil retention (92.9%) and encapsulation efficiency (98.60%) were identified as: CPI concentration of 2.1%, cumin oil concentration of 14.8% and MD concentration of 35%. Moreover, GC-MS analysis of obtained microencapsulates was also carried out to determine the changes in essential oil composition during spray drying. It was observed that cymene, α-pinene, β-pinene, sabinene, terpinene, terpineol, phellandrene, and cumin aldehyde were the major volatile components in cumin oil. It was observed that optimized design not only had the highest encapsulation yield, but also provided better protection against the degradation of volatile composition of cumin oil.
Evaluation on techno-functional, fatty acids and in vitro antioxidant activity of edible house cricket (Acheta domesticus)

(Graduate School, 2022-03-09) Hacıhasanoğlu, Furkan Ediz ; Özçelik, Beraat ; 506191509 ; Food Engineering

Since prehistoric times, insects have been eaten by humans at every stage of their life, including eggs, larvae, pupae and adults. The main reason for this was that people did not have the necessary tools for hunting or farming. The use of insects for human consumption, as mentioned, is called entomophagy. The origin of this word is basically a combination of two Greek words, "ἔντομον (éntomon)" meaning "insects" and "φᾰγεῖν (phagein)" meaning "food". Currently, approximately 2.5 billion people worldwide engage in insect-eating action. In contrast, insect consumption in Europe is very low. It is thought that the rapidly increasing world population will reach 9.8 billion by 2050. Therefore, current food production needs to be doubled to ensure adequate food supply for the estimated population. This means that both land and water resources begin to become insufficient. On a dry basis, the protein part of insects is between 50% and 82%, and essential and semi-essential amino acids have made them an important food source. They also have a significant amount of lipids on a dry basis; Some insects, among all other sources of lipids, contain very high amounts of fat, up to 75% and carbohydrate value of insects between 6-16%, which contain high levels of glycogen and chitin. They usually contain a good amount of minerals, to be more specific, some insects have iron and calcium values that surpass livestock and also contain good amounts of zinc. The energy values of insects vary according to the amount of fat. Insects in the larval or pupal stage have more energy than adult insects due to their high fat content. In general, its energy values are similar to red meat, but not similar to pork, as it contains a large amount of fat. Insects have been applied to wounds, respiratory and stomach problems since ancient times, and there is little research on their functional properties. Insects possess many bioactive materials; They have attracted more attention from researchers due to their contents such as peptides, polysaccharides, fatty acids and phenols. Moreover, peptides obtained from insect proteins have been shown to have health benefits such as antihypertensive, antimicrobial and antioxidant properties. In vitro antioxidant properties of insects have shown that their protein hydrolysates exhibit similar antioxidant properties to fish, wheat and flaxseed protein hydrolysates. On the other hand, insects bring with them some risk factors when used for human consumption, as they may have some pathogenic microorganisms that carry disease. Moreover, from an industrial point of view, proteins are needed in many areas due to their techno-functional properties. Accordingly, insect proteins can be used to meet such needs. A. domesticus is an insect species that belongs to the Orthoptera order and its common name is "house cricket". Although A. domesticus can be found all over the world, its origin is in Southwest Asia. In the context of the textural, nutritional and taste aspects of this species, it is produced especially in Thailand for use in the diets of individuals. Previously, studies on house crickets were predominantly done for animal feed substitutes, but as times have changed, there is now more room to be studied for human food as well. In the thesis study, the techno-functional properties of A. domesticus were observed as flour, defatted flour, or protein extract obtained from flour. The water and oil binding capacity were performed in both defatted flour and flour. Water binding capacities were found 1.91 gwater/g for defatted insect flour, and 1.41 gwater/g for insect flour. While the oil binding capacity was 1.37 goil/g for defatted insect flour, and 0.93 goil/g for insect flour. The foam capacities of the extracted protein and insect flour were found to be 148.33% and 6.67%, respectively, while the foam stabilities were found to be 91.60% and 97.66%, respectively. The protein extracts of A. domesticus flour were studied at different pH (3-5-7) and different concentrations (0.1%, 0.08%, 0.06%, 0.04%, 0.02%) to find out the emulsifying activity, stability and capacity. In the results examined, the activity varied between 0% and 52.63%. All concentrations at pH 9 showed the highest activity with no significant difference between them. On the other hand, the highest emulsification stability was observed in pH 9 sample containing 85.46% and 0.1% protein. While the emulsifying capacity was observed in the samples at the highest pH value, it was observed that there was an inverse proportion between the protein concentrations and the capacity at this pH. Protein solubility was investigated on insect flour at different pH (3-5-7-9) of different salt concentrations (0% and 3%). Results varied between 2.85% and 52.32%. The highest solubility value was found at pH 9(0%) salt, while the lowest value was found at pH 5(0%). Although the addition of salt at pH 9 significantly reduced the solubility, it remained to show higher solubility than other pH values. A. domesticus flour was analyzed for its fatty acid composition, and cis-linoleic acid (C18:2n6) showed the highest fatty acid value with 35.77% it was followed by palmitic (C16:0) and cis-oleic acid (C18:1n9) with 26.46% and 25.85%, respectively. Linolenic acid (C18:3n3) and cis-linolenic acid (C18:3n6) were found to be 1.04% and 0.27%, respectively. The lowest fatty acid composition was observed as 0.21% for heptadecanoic acid (C17:0). Some saturated fatty acids were also found, such as myristic acid (C14:0), palmitic acid (C16:0), palmitoleic acid (C16:1), stearic acid (C18:0) and heneicosanoic acid (C21:0). As a result of the DPPH analysis performed after in vitro gastrointestinal digestion, the IC50 (mg/ml) value was found to be too high as 31.96 for the stomach and 78.27 for the intestine. Inhibition percentages were found as 78.3% and 31.96% for the stomach and intestines, and values in terms of Trolox equivalent were observed as 3.62 mgTE/g in the stomach and 1.54 mgTE/g in the intestine. The results of this thesis clearly showed that A. domesticus flour and its derivatives showed potential as techno-functional. In addition, various fatty acid content and moreover, antioxidant properties obtained as a result of in vitro gastrointestinal digestion were similar to the results in the literature on health and showed that it could be used in this direction.
DBUVC ve UVCLED ışınlamanın kiraz ve vişne yüzeyinde mikrobiyel inaktivasyona ve meyve kalite özelliklerine etkisi

(Lisansüstü Eğitim Enstitüsü, 2022-04-21) Bilgin, Ayşenur Betül ; Akocak Başaran, Pervin ; 506181502 ; Gıda Mühendisliği

Ultraviyole – C (UVC), fiziksel bir yöntem olan ve genellikle gıdalarda dezenfeksiyon amaçlı kullanılan mor ötesi ışıktır. Son yıllarda, geleneksel düşük basınçlı UVC (DBUVC) lambaların ve son yıllarda yeni UVC kaynağı olarak kullanılan UVC – ışık yayan diyotların (light-emitting diodes, LED) (UVCLED) gıdalarda meyve ve sebze dezenfeksiyon çalışmaları yoğunluk kazanmıştır. Bu projede, UVC kaynağı olarak UVCLED ve DBUVC ışınlanmasıyla kiraz ve vişne yüzeyinin dezenfeksiyonun sağlanması ve meyvelerin raf ömrünün arttırılması hedeflenmiştir. Kiraz ve vişne yüzeyine daldırma ve spreyleme yöntemi ile Pseudomonas syringae, meyveden izole edilen maya inoküle edilmiştir. Meyve yüzeyinde doğal olarak bulunan toplam aerobik mezofilik bakteri (TAMB), toplam küf ve maya (TKF) ve inoküle edilen mikroorganizmalar hedeflenerek meyve yüzeyi 30 saniye, 3 ve 10 dakika UVCLED (200 – 260 nm) ve DBUVC (253,7 nm) ile ışınlanmıştır. Her iki UVC lamba ile ışınlanmış meyveler, 25-28˚C (%40-60 nem)'de ve +4˚C'de depolanarak mikroorganizmalardaki inaktivasyon etkisi periyodik olarak değerlendirilmiş ve ürünlerin raf ömrü incelenmiştir. Işınlama öncesi ve sonrası meyvelerde meydana gelen fizikokimyasal (meyve ağırlığı, pH, toplam çözünebilir katı madde miktarı, su aktivitesi, toplam fenolik madde miktarı, antioksidan aktivite ve renk) değişimler gözlenmiştir. Tüm bu sonuçlar ile UVCLED ve geleneksel DBUVC lambaların inaktivasyon etkinliği ve kalite üzerinde etkisi karşılaştırılmıştır. 3 ve 10 dakika DBUVC ışınlamanın, UVCLED'e göre, 30 saniye UVCLED ışınlamanın ise DBUVC'ye göre daha etkili olduğu tespit edilmiştir. Toplamda tüm sürelerde ve mikroorganizmalarda en düşük ve en yüksek inaktivasyon UVCLED ışınlama ile 0,31 – 0,86 kob/g, DBUVC ile 0,11 – 1,56 kob/g olarak gerçekleşmiştir. Hem kiraz hem de vişnede ışınlama öncesi ve sonrası toplam ağırlık, su aktivitesi, pH, toplam çözünür katı madde miktarı ve renk değerlerinde (L*, a*, b* ve H˚) önemli bir farklılık bulunmamıştır (p > 0,05). Vişnede UVCLED ışınlama ile fark edilebilir düzeyde (∆EUVCLED* = 1,17 – 3,30) renk değişimi tespit edilmiştir. Toplam fenolik madde ve antioksidan madde miktarında çoğunlukla önemli bir artış gözlemlenmiştir (p < 0,05). Işınlanmış meyvelerin +4 ve 25˚C'de depolanmasıyla raf ömrünün ortalama %30 oranında arttığı tespit edilmiştir. Sonuç olarak; DBUVC, UVCLED ışınlamaya göre genel olarak mikroorganizma inaktivasyonunda daha etkili olduğu, antioksidan aktivitesi ve toplam fenolik madde miktarının artması dışında meyvelerin fizikokimyasal özelliklerinde önemli bir etkisinin bulunmadığı tespit edilmiştir.
Mercimek proteini ile soğan kabuğu fenolikleri interaksiyonunun fonksiyonel özellikler ve biyoaktivite üzerine etkisi

(Lisansüstü Eğitim Enstitüsü, 2022-04-24) Köroğlu, Deniz Günal ; Güven Çapanoğlu, Esra ; Gıda Mühendisliği

Fenolik bileşikler bitkilerde bulunan antioksidan özelliğe sahip bileşiklerdir. Tüketicilerin sağlıklı tercihlere yönelmesi ile birlikte, bitkilerden saflaştırılan fenolik bileşikler özellikle sentetik antioksidanlar yerine veya fonksiyonel gıdalarda bileşen olarak kullanılmaktadır. Bunun yanında, her geçen gün büyümekte olan gıda sektöründe büyük oranlarda gıda atıkları oluşmakta ve çevre kirliliği gibi birçok soruna neden olmaktadır. Doğal bir kaynak olan gıda atıklarından fenolik bileşiklerin geri kazanılması, gıda atıklarının tekrar kullanılması için olanak sağlamaktadır. Özellikle işlenmiş soğana talebin son yıllarda artması, soğan atıklarının çoğalmasına sebep olmuştur. Soğanın iç kısmının fenolik bileşikler yönünden zengin olmasına karşın benzer fenolik profiline sahip olan kabuk kısmının fenolik madde miktarı daha fazladır; fakat bu kısım gıda hazırlama sürecinde atılmaktadır. Bu çalışmanın amacı (1) floresan sönümleme ile mercimek proteini~soğan kabuğu fenolik ekstraktı kompleks oluşum mekanizmasını analiz etmek, in-vitro gastrointestinal sindirilebilirlikleri ile birlikte (2) model sistemlerde protein fonksiyonel özellikleri üzerine etkisini ve (3) fonksiyonel bir gıda ürününde kompleks oluşumunun etkilerini tanımlamaktır. İlk aşama olarak, mercimek proteinleri ile fenolik ekstraktların kompleks oluşum mekanizması hakkında bilgi almak amacıyla floresan sönümle analizi yapılmıştır. Her iki ekstraktın, mercimek proteinlerinin floresan yoğunluğunda konsantrasyonlarına bağlı olarak düşmeye sebep olduğu belirlenmiştir. Ayrıca, kırmızı soğan kabuğu fenolik ekstraktının sarı soğan kabuğu fenolik ekstraktına kıyasla daha düşük konsantrasyonlarda sönümleme etkisi olduğu belirlenmiştir. Mercimek proteini~sarı soğan kabuğu fenolik ekstraktı kompleksi için mercimek proteininin maksimum emisyonunda maviye kayma olmuştur. Diğer bir deyişle, interaksiyona giren fenolik grubunun proteinin içinde gömülü olduğunu göstermiştir. Ayrıca, kompleks oluşumu doğrusal bir Stern-Volmer grafiği ile statik söndürmeyi ifade etmektedir. Mercimek proteini~sarı soğan kabuğu fenolik ekstraktı kompleksinin termodinamik parametreleri hesaplanmıştır. Etkileşimin baskın olarak hidrofobik, entalpi güdümlü olduğu ve kendiliğinden gerçekleşmediği bulgusuna ulaşılmıştır. Mercimek proteini~kırmızı soğan kabuğu fenolik ekstraktı kompleksi için kırmızıya kayma, yani proteinlerin yapısal açılımını ifade etmektedir. Diğer bir yandan, Stern-Volmer grafiği doğrusal değildir. Dinamik ve statik olmak üzere iki sönümleme mekanizmasının mercimek proteini~kırmızı soğan kabuğu fenolik ekstraktı kompleksi için aynı anda meydana geldiği "eylem alanı modeli" (sphere of action) söz konusudur. Çalışmanın ikinci aşamasında, protein-fenolik interaksiyonunun mercimek proteinlerinin fonksiyonel özellikleri üzerine ve farklı sistemlerin (fenolik ekstrakt çözeltileri, protein-fenolik çözeltileri, emülsiyonlar) in-vitro gastrointestinal sindirilebilirliği üzerine etkileri araştırılmıştır. Fenolik bileşiklerin varlığı konsantrasyona bağlı olarak mercimek proteinlerinin çözünürlüğü, köpürme ve emülsiyon özelliklerini olumsuz etkilemiştir ve Pearson korelasyon katsayısı analizi ile fenolik konsantrasyonunun proteinlerin bu fonksiyonel özellikleri ile ilişkisinin negatif olduğu da belirlenmiştir. Farklı model sistemlerde (fenolik ekstrakt çözeltileri, protein-fenolik çözeltileri, emülsiyonlar) in-vitro gastrointestinal sindirim öncesi, toplam fenolik madde miktarları büyükten küçüğe sırasıyla ekstrakt çözeltisi, emülsiyon ve protein-fenolik çözeltisi şeklindedir. Mercimek proteini varlığında toplam fenolik madde miktarında düşme vardır. Toplam fenolik madde miktarı mide fazından sonra ekstrakt çözeltileri ve emülsiyonlarda düşmüştür ve protein-fenolik çözeltilerinde ise sindirim öncesi değerlere benzerdir. Bütün çözelti sistemlerinde, aynı çözelti için toplam fenolik madde miktarı bağırsak fazında en yüksektir. Antioksidan aktivite değerleri toplam fenolik madde sonuçları ile benzer değişmiştir. Protokateşik asit ve fenolik asit türevleri çözelti içerisindeki diğer fenolik bileşiklerin parçalanmasından dolayı sindirim öncesi değerlerinin neredeyse iki katı olmuştur. Kırmızı soğan kabuğu fenolik ekstraktında belirlenmiş her bir antosiyaninin miktarı sindirim öncesinde emülsiyon~ekstrakt çözeltisi>protein-fenolik çözeltisi şeklinde iken mide fazından sonra emülsiyon>ekstrakt çözeltisi~protein-fenolik çözeltisi şeklindedir. Bağırsak fazından sonra ise ekstrakt çözeltilerindeki antosiyanin miktarı diğerlerine kıyasla daha fazladır. Antosiyaninler protein içeren sistemlerde sindirim sonunda daha az tanımlanabilmiştir. Mercimek proteinlerinin varlığıyla sindirim öncesi her bir fenolik bileşiğin miktarında azalma gözlenmiştir. Bu azalma kuersetin ve türevleri için daha fazla olmuştur. Mide fazından sonra kuersetin ve türevlerinin miktarı düşmüş, bağırsak fazından sonra mide fazına benzer olmuştur. Bu durum, toplam fenolik madde miktarında ve antioksidan kapasitesinde gözlemlenen belirgin düşmenin sebebi olarak düşünülmüştür. Tüm sistemlerde bağırsak fazından sonra kuersetin tespit edilmezken, kuersetin türevleri emülsiyonlarda en yüksektir. Protein varlığında, model bir sistemde, her bir fenolik bileşiğin in-vitro gastrointestinal sindirimden farklı etkilendiği gözlenmiştir. Üçüncü aşamada, iki farklı oranda fenolik (soğan kabuğu tozu, soğan kabuğu fenolik ekstraktı ve kuersetin) içeren fonksiyonel krakerlerde fenolik içerikte/antioksidan aktivitede değişim protein-fenolik interaksiyonları dikkate alınarak değerlendirilmiştir. Fonksiyonel krakerler benzer besin değerlerine (p>0.05), daha düşük L* ve daha yüksek a* değerlerine sahiptir. b* değeri daha yüksek oranda soğan kabuğu tozu veya soğan kabuğu fenolik esktraktı ile düşmüş, kuersetin katkısı ile artmıştır. Fonksiyonel krakerlerde fenolik/antioksidan geri kazanımı fenolik oranı arttıkça azalmıştır ve kuersetin 7,4-diglikozit miktarı teorik değerden düşük bulunmuşken kuersetin miktarı yüksektir. İn-vitro gastrointestinal sindirim krakerlerde uygulanmıştır ve fenolik/antioksidan/protein ulaşılabilirliği belirlenmiştir. Fenolik (BIF) ve antioksidan (BIA) biyoerişilebilirlik indeksi in-vitro gastrointestinal sindirim öncesi ve sonrası toplam fenolik madde miktarı ve antioksidan aktiviteye göre hesaplanmıştır. Fonksiyonel krakerlerde BIF değeri küçükten büyüğe soğan kabuğu tozu, soğan kabuğu fenolik ekstraktı ve kuersetin eklenen krakerler şeklinde iken, BIA değerleri kuersetin eklenen krakerlerde en düşüktür. Kuersetin sadece soğan kabuğu fenolik ekstraktı içeren buğday veya mercimek krakerinde tanımlanabilmiştir. Ağız ve mide fazında tüm fonksiyonel buğday krakerlerinde TCA'da çöken peptid miktarı kontrolden küçüktür. Sindirim sonunda buğday krakerlerinin TCA'da çöken peptitleri tanımlanamamıştır. Ağız fazından sonra fonksiyonel mercimek krakerlerinin TCA'da çöken peptid miktarı birbirine yakın (p<0,05) kontrolden küçüktür, mide fazından sonra ise fazladır. Bağırsak fazından sonra TCA'da çöken protein miktarı kuersetin içeren mercimek krakerinde en düşüktür. Gastrointestinal sindirim boyunca genel olarak TCA'da çöken peptid miktarı azalırken, serbest amino grupları miktarında artış gözlenmiştir. Ağız fazından sonra serbest amino grupları miktarı kontrol krakerlere istatistiksel olarak benzer olmuştur (p<0.05). Mide ve bağırsak fazından sonra ise buğday krakerlerinde kontrole kıyasla daha düşük miktarda serbest amino grupları miktarı saptanmıştır. Mide fazından sonra fonksiyonel mercimek krakerlerinin serbest amino miktarı kontrolden yüksektir, bağırsak fazından sonra ise düşüktür. Sonuç olarak, sarı ve kırmızı soğan kabuğu fenoliklerinin mercimek proteinleri ile interaksiyon mekanizması bu çalışma ile ilk defa araştırılmıştır ve her iki ekstraktın farklı yollarla interaksiyona girdiği belirlenmiştir. Bu doktora çalışması, soğan kabuğu fenoliklerin mercimek proteinlerinin fonksiyonel özellikleri üzerine belirgin etkisi olduğunu ve özellikle protein varlığında fenoliklerin biyoerişilebilirliğinin hem model sistemlerde hem de bir gıda matriksinde önemli ölçüde etkilendiğini gösteren özgün bir çalışmadır.
Yumurta bileşenlerinin kek hamuru reolojisine ve kek tekstürüne etkilerinin incelenmesi

(Lisansüstü Eğitim Enstitüsü, 2022-05-15) İnanlar, Batuhan ; Altay, Filiz ; 506191504 ; Gıda Mühendisliği

Endüstriyel kek üretiminde, tüm proses parametreleri aynı kalmasına rağmen kullanılan yumurtanın değişimi sonucunda ürünün kalitesinde farklılıklar gözlemlenmektedir. Kalitedeki farklılıklar, standart bir ürün elde etmeyi zorlaştırmaktadır. Bu kapsamda, farklı tedarikçilerden alınan yumurtaların bileşenlerinin kek hamuru reolojisine ve kek tekstürüne etkisi incelenerek farklılığın temelindeki sebeplerin bulunması amaçlanmıştır.
Bakladan ultrases destekli alkali ekstraksiyon ile protein eldesi: Teknofonksiyonel, in vitro biyoerişebilirlik ve ade inhibisyon özelliklerinin incelenmesi

(Lisansüstü Eğitim Enstitüsü, 2022-05-30) Mertdinç, Zehra ; Özçelik, Beraat ; 506181516 ; Gıda Mühendisliği

Son yıllarda nüfus artışı, gıda kaynaklarının tükenmesi, iklim değişikliği ve hayvan hakları gibi birçok sebepten dolayı hayvansal gıda kaynaklarına alternatifler aranmaya başlamıştır. Bitkisel diyetlerin çevresel ve ekonomik katkılarının yanı sıra, kardiyovasküler hastalıklar, Tip-2 diyabet, obezite ve hipertansiyon gibi hastalıkların önlenmesinde de etkili olduğu bilinmektedir. Bakla, ülkemizde genellikle Ege, Marmara ve Akdeniz bölgelerinde üretimi yapılan, besleyici değeri yüksek ve biyoaktif bileşenler açısından zengin bir bitkisel protein kaynağıdır. Gıdaların besleyici ve fonksiyonel özelliklerinin geliştirilmesi için bakliyatlardan protein konsantresi/izolatı elde edilmektedir. Bu amaçla, özellikle alkali ekstraksiyon ve izoelektrik noktada çöktürme metodu sıklıkla kullanılan yöntemlerden biridir. Aynı zamanda bu yöntemler, ultrases, mikrodalga ve enzim destekli uygulamalar ile daha verimli hale getirilmektedir. Elde edilen proteinlerin, gıda matrisinde uygulamaları, depolanması ve işlenmesi noktasında teknofonksiyonel özelliklerinin (su/yağ tutma, köpürme kapasitesi/stabilitesi, çözünürlük gibi) incelenmesi gerekmektedir. Bu çalışmada da İzmir'de yetiştirilmiş bir bakla türünden alkali ekstraksiyon ve alkali ekstraksiyon öncesi ultrases uygulaması ile elde edilen protein konsantrelerinin teknofonksiyonel özellikleri incelenmiştir. Gıdalardan biyoaktif peptilerin eldesinde pepsin, alkalaz, tripsin gibi enzimler kullanılarak hidrolizasyonu gerçekleştirilebilir. Elde edilen hidrolizatlar, aminoasit dizilimleri, büyüklükleri ve bazı fizikokimyasal özelliklerine bağlı olarak anti-hipertansif, anti-oksidan ve anti-mikrobiyal etki gösterebilirler. Aynı zamanda hidrolize uğrayan peptitlerin insan vücudunda in vitro gastrointestinal sindirimin ardından biyoerişilebilirlikleri de etkilenmektedir. Bu çalışmada da alkali ve ultrases destekli alkali ekstraksiyonla elde edilen protein konsantrelerine pepsin ile enzimatik hidrolizasyon uygulanmış, ardından elde edilen hidrolizatlarda da in vitro protein biyoerişilebilirliği ve anti-hipertansif etkisinin belirlenmesi amacıyla ADE inhibisyon analizi uygulanmıştır. Bu çalışmada elde edilen sonuçlara göre, %27,32 protein miktarına sahip olan bakla unundan, alkali ve ultrases destekli alkali ekstraksiyonla sırasıyla %65,93 ve %75,04 protein içeriğine sahip konsantratlar elde edilmiştir. Ekstraktların teknofonksiyonel içerikleri de incelendiğinde, alkali ve ultrases destekli uygulamalar sonucunda ekstraktlarda protein çözünürlüğü, su ve yağ tutma kapasiteleri, köpürme stabiliteleri gibi özellikleri geliştirilmiş olup, çoğu uygulamada da ultrases uygulamasının alkali konsantrelerden istatistiksel olarak anlamlı bir farklılık gösterdiği tespit edilmiştir. Ayrıca hammadde, ekstraktlar ve enzimatik yöntemlerle elde edilen hidrolizatların, in vitro gastrointestinal sindirim sonrasındaki protein biyoerişilebilirlikleri incelenmiştir. Bu çalışmada da en yüksek protein biyoerişilebilirliği %46,39 ile ultrases destekli hidrolizatlarda tespit edilmiştir. Öte yandan, hidrolizatlarda ADE inhibisyon değerleri hesaplanarak baklanın potansiyel anti-hipertansif etkisi incelenmiştir. Analizler sonunda sırasıyla alkali ve ultrases yöntemlerinden elde edilen hidrolizatların IC50 değerleri 504,42 ve 222,89 μg/ml olarak hesaplanmıştır. Elde edilen sonuçlar göstermiştir ki, ultrases uygulaması ile ADE inhibisyon aktivitesinin arttığı gözlemlenmiştir. Özetle, bu çalışma ile Türkiye'ye özgü bir bakla türünden iki farklı yöntemle ekstrakte edilen proteinlerin teknofonksiyonel özellikleri tanımlanmış olup, enzimatik hidrolizasyonu ile de in vitro biyoerişilebilirlik ve ADE inhibisyon potansiyelleri incelenmiştir. Sonuç olarak, ultrases teknolojisinin, proteinlerin bazı teknofonksiyonel özellikleri, protein biyoerişilebilirliği ve anti-hipertansif etkileri üzerindeki olumlu etkileri incelenmiş ve gıda uygulamalarındaki potansiyeline dair bir bakış açısı geliştirilmesi hedeflenmiştir.
Nar kabuğundan enzim ve ultrason destekli ekstraksiyon yöntemi ile fenolik madde ve pektin elde edilmesi

(Lisansüstü Eğitim Enstitüsü, 2022-06-15) Kahveci, Zeynep Merve ; Karıncaoğlu Kahveci, Derya ; 506191514 ; Gıda Mühendisliği

Günümüzde, gıda kaynaklarının azalması, nüfusun hızla artışı gibi sebeplere bağlı olarak gıda atıklarının azaltılması ve atıklardan katma değeri yüksek bileşenlerin geri kazanımı önem kazanmaktadır. Geri kazanım alanında metotların geliştirilmesi ile birlikte, sürdürülebilir ve çevre dostu üretim kavramları da gündeme gelmeye başlamıştır. Çevre dostu metotlar arasında yer alan enzim ve ultrason destekli ekstraksiyon; çözgen kullanımını azaltarak, daha az enerji sarfiyatı sağlayarak ve verimi artırarak fayda sağlamayı amaçlamaktadır. Meyve sebzeler gıda atıklarının büyük bir çoğunluğunu oluşturduğu için geri kazanım konusunda pek çok çalışmaya konu olmaktadırlar. Nar kabuğun, meyvenin yaklaşık yarısını oluşturması ve değerli bileşenler bakımından zengin olması ile bu çalışmada tercih edilmiş; endüstriyel nar suyu üretiminden arta kalan nar kabuğundan fenolik madde ve pektin ekstraksiyonu için enzim ve ultrason destekli ekstraksiyon yöntemleri kullanılarak optimum koşullar belirlenmiştir. Öncelikle, enzimin hücre duvarını parçalaması özelliğinden faydalanılarak nar kabuğundan fenolik madde ekstraksiyonu için optimum enzim ön işlem süresi 60 dk, sonrasında etanol ile ekstraksiyon süresi ise 30 dk olarak belirlenmiştir. Çeşitli katı:sıvı oranı ve enzim konsantrasyonu seviyelerinde yapılan esktraksiyon sonucunda,optimum katı sıvı oranı 1:40, enzim konsantrasyonu %6 (%v/m) olarak belirlenmiştir ve bu koşullarda 329,5±37,8 mg GAE/g fenolik madde konsantrasyonu elde edilmiştir. Belirlenen bu optimum koşullarda elde edilen fenolik maddelerin profili HPLC ile çıkarılmış, baskın olarak punikalajin, gallik asit, ellagik asit ve (-)-apigallokateşin içerdiği tespit edilmiş ve antioksidan aktivite CUPRAC ve DPPH metotları ile tayin edilerek sırasıyla 3108,5±303 mg TE/g ve 1586±15,9 mg TE/g olarak tespit edilmiştir. Elde edilen fenolik madde verimi ve antioksidan aktivitesinin enzim kullanılmayan klasik yönteme kıyasla daha yüksek olduğu tespit edilmiştir. Projenin amacı çevre dostu bir metotla birden çok fraksiyonda geri kazanımı sağlamak olduğu için, fenolik madde ekstraksiyonu gerçekleştirildikten sonra kalan nar kabuğundan pektin ekstraksiyonu gerçekleştirilmiştir. Ultrason kullanımının kavitasyon etkisi ile hücre duvarını parçalayarak verimi artırdığı tespit edilmiş ve yapılan optimizasyon çalışmasında 1:20 katı sıvı oranı ve 45 dk süre ile gerçekleştirilen ultrason ön işlem sonucunda 3,7±0,002% ile maksimum verim elde edilmiştir. Elde edilen pektinin karakterizasyonu için galakturonik asit oranı ve esterleşme derecesi analiz edilmiştir. %18,2±1,4 galakturonik asit oranı ve %74±0,07 esterleşme derecesi elde edilmiş; yüksek metoksipektin olduğu ve şeker varlığında jelleşebileceği tespit edilmiştir. Bu kriterlere bakıldığında, geleneksel metot ile direk olarak nar kabuğundan elde edilen pektine kıyasla önemli bir farklılık olmadığı görülmüştür. Çalışma sonucunda, enzim ve ultrason ile ön işlem uygulamasının fenolik madde ve pektin verimini artırabileceği tespit edilmiştir.
Biological control of Aspergillus flavus growth and its aflatoxin b1 production by antagonistic yeasts

(Graduate School, 2022-06-29) Dikmetaş, Dilara Nur ; Güler Karbancıoğlu, Funda ; Özer, Hayrettin ; 506181504 ; Food Engineering

The presence of mycotoxins in food and feed poses a risk to human health and animal productivity and result large economic losses. In the field and during storage period, Aspergillus flavus infect grains. Aflatoxin B1, is classified as group 1 carcinogen, having hepatotoxic, genotoxic, and teratogenic properties, may be produced by generally A. flavus and Aspergillus parasiticus in addition to grain deterioration and yield loss. Aflatoxins have been found in a variety of foods including oilseeds, nuts, dried figs and spices. Dried figs, pistachios, hazelnuts and groundnuts cultivated in Turkey are risky products in terms of aflatoxins. The application of synthetic fungicides is the most common method for controlling decay in most crops. However, because of the fungal resistance and detrimental impacts on human and animal health, as well as the environmental concerns in general, their use is being tried to diminished. Due to these concerns, researchers have tended to investigate more eco-friendly and healthy methods to manage fungal diseases. As a result, detecting and preventing Aspergillus species contamination, as well as lowering the level of aflatoxins in foodstuffs used in many agricultural products. To reduce usage of synthetic fungicide, biological control is an important strategy as a promising alternative with low environmental impact in reducing fungal infection and mycotoxin production in the field and during postharvest period. In addition, among microorganisms, yeast species have been extensively studied as antagonist due to simple nutritional requirements, able to colonize dry surfaces for long periods of time and able to grow rapidly in bioreactors with inexpensive substrates. Furthermore, yeast is simply adapted to microenvironments. The crucial and most important step is to develop biocontrol agent is isolation and screening of yeast isolates. Antagonistic yeasts have been showed several different mechanism to control of different moulds such as competition for space and nutrients, biofilm formation, parasitism, production of antimicrobial volatile organic compounds and production of lytic enzymes. The antagonist mechanism generally explained with cell wall-degrading enzyme synthesis including chitinases, β-1,3-glucanase, protease, cellulase and pectinase. Yeasts with high cell wall degrading enzyme activity, also showed high biocontrol efficacy. Biocontrol of aflatoxin has been generally documented by non-aflatoxigenic Aspergillus species. However, the studies to control Aspergillus flavus by yeasts limited. In various industrial processes, the Metschnikowia yeast has wide range of biotechnological application and generally isolated from fruits and flowers. Several Metschnikowia based biocontrol products have been industrialized to control postharvest diseases including Botrytis or Monilinia spp. However, only a few biocontrol agents are converted into industrial products. Meyerozyma, Moesziomyces and Metschnikowia sp. yeasts antifungal activity have been studied by several researchers. Among antagonistic microorganism mechanism of action, production of antimicrobial volatile organic compounds is one of the least studied. Primarily, volatile organic compounds produced by antagonistic yeasts have great potential used as biocontrol agents of filamentous fungi. In this study, four yeast isolates have been isolated and identified by different plant parts including hawthorn, hoşkıran, bean and grape leaf collected from Turkey different region. Four previously isolated and identified isolates from grapes, blueberry have been also included in this study. The eight antagonistic yeasts have been belong to Moesziomyces sp., Meyerozyma sp. and Metschnikowia sp. Yeasts secrete fungal lytic enzymes which are typically associated with biocontrol mechanism. Lytic enzyme activities of yeasts were examined with screening method. All of the isolates have β-glucosidase and chitinase activity, which are crucial for antifungal mechanism, however absence of the pectinase activity. Among antagonistic yeasts, only Metschnikowia pulcherrima (26-BMD) found as protease negative. Dual culture assay have been conducted to observe antagonistic effect of yeasts against aflatoxin B1 producer Aspergillus flavus. All of the antagonistic yeasts formed inhibition zones in dual culture assay against to Aspergillus flavus due to secretion of diffusible antifungal compounds. After that, yeasts antifungal and antiaflatoxigenic impact on aflatoxin producer Aspergillus flavus by spot inoculation method with different incubation period by in vitro studies. Different yeasts used to investigate to control Aspergillus flavus growth. In addition to that, origin of the yeast affect their biocontrol efficacy. All of the antagonistic yeasts formed inhibition zones in dual culture assay against to Aspergillus flavus due to secretion of diffusible antifungal compounds. While Aspergillus flavus mycelial growth of inhibition 86-97% after three days. All isolated and identified yeasts were effective to control Aspergillus flavus, as well as aflatoxin. Aflatoxin B1 production was reduced from 1773 ng/g (in control samples) to 1.26-10.15 ng/g with the application of antagonistic yeast. Metschnikowia aff. pulcherrima (32-AMM) was found as the most effective yeasts to inhibit mycelial growth of Aspergillus flavus among other yeasts. In addition, yeasts plant origin and incubation period also affect their inhibition potential (p<0.05). All of the yeasts might be used as biocontrol agent against Aspergillus flavus growth. Additionally, all of the yeast volatile organic compounds (VOCs) reduced sporulation however among antagonistic yeasts only Moesziomyces bullatus (DN-FY), Metschnikowia aff. pulcherrima (DN-MP) and Metschnikowia aff. pulcherrima (32-AMM) were reduced Aspergillus flavus mycelial growth with in vitro studies. But only VOCs produced by Metschnikowia aff. fructicola (1-UDM) was also found effective in reduction of Aflatoxin B1 production in in vitro experiments. This activity was associated to different volatile organic compounds. As a result, more investigation into the role of volatile organic compounds in Aspergillus flavus and aflatoxin B1 control is required. Further field experiments would indicate yeasts biocontrol potential on the products prone to contaminated from Aspergillus flavus. By the way, also isolation of volatile organic compounds from yeasts should be used to protect products from contamination without harmless to humans and environmentally friendly.
Encapsulation of echium oil and saffron extract in electrospun nanofibers

(Graduate School, 2022-11-15) Najafi, Zahra ; Yeşilçubuk Şahin, Neşe ; Altay, Filiz ; 506152510 ; Food Engineering

In this doctoral thesis, it was aimed to investigate the production of nanofibers containing Echium seed oil and bioactive compounds of saffron using biopolymers, the characterization of nanofibers and the in vitro release and kinetic studies of obtained nanocarriers. In addition, the different applications of nanofibers (carrier system or food coating material) were studied. Bioactive compounds possess many health promoting properties, therefore there is a growing interest in development of functional foods fortified with them. Echium seed oil is an important plant-origin source of long chain polyunsaturated fatty acids (LC-PUFAs), especially stearidonic acid (SDA). The importance of SDA, is due to its function as a precursor in biosynthesis of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and its conversion efficiency to EPA (30 %) is higher than ALA (around 7%). Moreover, they have anti-cancer activity, and they probably reduce coronary diseases and immune disorders. Saffron is also attracting consumers' attention due to including valuable bioactive compounds exert important health-promoting effects. Crocins, picrocrocin, and safranal are the three main bioactive ingredients present in saffron stigmas and they exhibited antioxidant, antitumor and neuroprotective activities. Therefore, in this thesis study, electrospinning as an emerging electrohydrodynamic method, has been applied for encapsulation of PUFAs and saffron extract (SE), in addition the potential of SE as a natural antioxidant to enhance oxidative stability of encapsulated oil in nanofibers was evaluated. First, saffron bioactive compounds were extracted by conventional and novel approaches using different solvents, then the extract with the highest antioxidative activity was freeze-dried and incorporated into several edible oils to retard their lipid oxidation measured by Rancimat test (Chapter 3). Then, in Chapter 4, it was aimed to produce nanofibers from SE and EO by electrospinning using different coating materials. The electrospun Pul-Pec and Pul-PPI-Pec nanofibers (NFs) loaded with SE, SE loaded nanoliposome (SENL) and EO emulsion were produced using water as a solvent. Morphological studies by scanning electron microscopy (SEM) showed that uniform Pul-Pec and Pul-PPI-Pec NFs with average diameters of 112 nm and 115 nm were fabricated, by the addition of EO, the diameters of fibers increased to 163 and 125 nm. Moreover, thicker fibers were formed by incorporation of both bioactive compounds (EO and SENL) into electrospinning blends. SE and EO embedded into the blend NFs had encapsulation efficiencies (EE) greater than 70% and 65%, respectively. The FTIR spectra of all NFs were recorded at various storage days (50°C), and the A 3010 cm-1/A 2925 cm-1 ratio were calculated for each sample. This ratio indicates the unsaturation degree of the encapsulated oil. The values of this ratio which was calculated for samples revealed an upward trend, and the largest values belonged to EO-loaded PPI-Pul-Pec NFs with SELN. Therefore, this encapsulant provided the best protection for EO against oxidation. Beside FTIR method, isothermal differential scanning calorimetry (DSC) method was used to determine the oxidative stability of EO and EO embedded in NF matrix. The onset oxidation times (Ot) were obtained from DSC exotherms of NF samples. Four different temperatures were used to calculate activation energy values (Ea) and to predict the shelf-life of EO loaded NF samples. The DSC outcomes were in consistent with FTIR results. Incorporating SENL in EO loaded Pul-PPI-Pec NFs caused up to a three-fold increase in Ot at 20°C compared to control samples (EO loaded Pul-PPI-Pec NFs without SE). In addition, the greatest Ea (100.8 Kj.mol-1) and longest shelf-life was observed for this sample. The release behavior of both bioactive compounds and the kinetics involved were evaluated by fitting the release profile data to different kinetic models such as Rigter-Peppas, Zero-order, First-order, and Higuchi. The crocin-4 release rate from SELN loaded NF blends (58–62% over 7 hours) was noticeably slower than that of unencapsulated SE (80% over 3 hours). Crocin-4 transfer from unencapsulated SE followed zero-order kinetics, although its release from NF samples followed Ritger-Peppas model involved Fick-diffusion mechanism. EO release from Pul-PPI-Pec NFs governed by a Fickian diffusion mechanism according to the best fitted model (Ritger-Peppas). However, for cross-linked Pul-Pec loaded EO NFs under simulated intestinal fluid, the release mechanism was non-Fickian which governed by combinations of diffusion and erosion. The release rate of EO was slower in cross-linked Pul-Pec NF blend due to their greater resistance against degradation. In Chapter 5, zein nanofibers (ZNs) loaded with SE were produced by electrospinning method, which were subsequently used as a nanocoating material. The influences of concentration and voltage are investigated on the electrospinning process. The zein polymer was prepared in three different concentrations (20, 25 and 30 wt%) through dissolving in ethanol-water (80:20) and then exposed to high voltages (6 and 14 kV). In addition, the solution properties including viscosity, surface tension and electrical conductivity of polymers were determined and correlated with the morphology of resulted fibers. SEM images showed that smooth and bead-free NFs were obtained via electrospinning of zein at 30% w/v concentration, while zein particles and mixtures of nanofibers and beads was generated from zein solutions at 15 and 20 wt% concentrations. Moreover, fibers obtained at applied voltage of 6 kV resulted in narrower fibers. Consequently, zein nanofibers (30 wt%) was selected as a carrier to encapsulate SE (5 and 10 wt% respect to zein weight). The resulted ZNs loaded with SE were characterized in terms of morphology, thermal and molecular properties, encapsulation efficiency and antioxidant activity. Addition of SE (10%) into ZNs caused a significant increase in mean fiber diameter from 369 to 440 nm at 6 kV. The encapsulation efficiency (EE) of SE components within ZNs was assessed by HPLC method. EE of total crocin and picrocrocin, in ZNs loaded with SE (ZNLSE10%), were 64% and 47%, respectively. Picrocrocin and four glycosyl esters of crocetin, namely trans-crocin-4, trans-crocin-3, cis-crocin-3, and cis-crocin-4, were detected in SE by LC-MS. The alteration in the crystal structure of SE was validated by DSC profiles, demonstrated that SE molecules were successfully embedded into the zein proteins. The FTIR spectra of ZNLSE, indicated the disappearance of several peaks because of shifting in signals and in plane-bending of hydroxyl groups, it can be proof for formation of secondary interactions between hydroxyl functional groups of crocins and amino groups (NH2) of zein. The ZNLSE (10 wt%) exhibited the greatest antioxidant activity compared to SE and ZN as controls. In final step, with the aim of exploring the efficiency of ZNLSE on shelf-life and quality of fish fillets, skinless fish fillets were nanocoated with ZNLSE (10%). Deterioration of the fish samples at 2 ± 1 °C during the 8-days-storage period was investigated through several physicochemical tests including volatile basic nitrogen (TVBN), thiobarbituric acid reactive substances (TBARS), peroxide value (PV), free fatty acid (FFA) and pH. The TVBN values of the coated samples were 30% lower than those of the control group on the 8th day of cold storage. Lipid oxidation in coated samples was also retarded according to the results of PV and TBARs analysis. In contrast to coated samples, PV of uncoated samples increased gradually from 1.3 to 4.4 meq O2/kg until the 4th day of storage, and then decreased until 8th day whereas PV of coated samples showed an increasing trend and reached to 3.27 meq O2/kg on 8th day, and their PV were lower than control. The FFA values of control and treated samples slowly increased throughout storage, however the rate of increase for FFA values remained slower than control. It has been concluded that zein based nanofibers loaded with SE have the potential as an active food packaging layer to extend the shelf life of fish fillets. In Chapter 6, the fabrication, characteristics, and release behaviors of SE (10 wt%) loaded zein, Pul-Pec, and Pul-PPI-Pec NFs were investigated. The morphology of three different NFs was investigated by SEM. The resulted NFs were smooth and homogenous without bead structure, and they had fiber diameters ranging from 103 to 115 nm. To observe the interactions of the bioactive compounds in saffron with various polymers as well as changes in the secondary structure of proteins, FTIR tests were also carried out. The in vitro release of crocin from NFs were kinetically studied under gastrointestinal media, with and without the digestive enzymes. Furthermore, in vitro release studies were performed using Franz diffusion cells in PBS solution. The fitting of in vitro release data into Ritger-Peppas model, indicated that crocin transfer followed Fickian diffusion mechanism for Pul-Pec and Pul-PPI-Pec NFs samples and non-Fickian for zein NFs. The release data belongs to in vitro release studies by Franz-diffusion cells best fitted with Ritgar-Peppas and Higuchi models, in addition the crocin release was governed by Fickian controlled diffusion transport. According to the results, it can be concluded that SE-loaded NFs have the potential to be used as a carrier to provide prolonged release of SE and maybe for transdermal applications as a food supplement. In the final part of the study, the general discussions and concluding remarks are given in Chapter 7 along with prospects and challenges.
Green extraction and encapsulation of black rosehip polyphenols: İn vitro bioaccessibility, bioavailability, and biological activities

(Graduate School, 2022-11-22) Kasapoğlu, Kadriye Nur ; Özçelik Günşar, Beraat ; 506152507 ; Food Engineering

Due to the increased prevalence of degenerative diseases, there has been a high consumer demand for functional foods with added health benefits. The term "functional food" generally refers to products providing an additional health benefit, beyond basic nutrition. Consuming foods fortified with functional ingredients (e.g., vitamins, probiotics, omega n-3 fatty acids, minerals, and antioxidants) could help to mitigate the risk of chronic diseases and contribute to the physical and mental well being. In that sense, (poly)phenols, phenolic compounds containing at least one phenolic hydroxyl group, are the most pronounced secondary metabolites found in plants possessing strong antioxidant power. However, to exploit the use of underutilized wild edible plant resources, convenient extraction methods need to be developed to separate and concentrate the (poly)phenols without using toxic hazardous chemical solvents. Hence, 'green' isolation of value-added ingredients for enrichment purposes from underutilized plant sources have importance for food industry. Moreover, (poly)phenols are susceptible to against harsh processing and environmental factors such as heat, oxygen, light, alkaline pH, or enzymes and therefore mostly have poor solubility and bioavailability. Moreover, their biological functions are significantly dependent on their bioavailability. In this regard, encapsulation applications enable increasing their stability by protecting from stresses mentioned above and/or improve their solubility, bioaccessibility and intestinal uptake which is especially desirable for manufacturing of functional foods/beverages and dietary supplements. Taking these facts into consideration, this thesis consist of the following objectives: (i) to characterize the (poly)phenols composition of black rosehip (Rosa pimpinellifolia L.) and its antioxidant as well as antiproliferative activity in comparison to common rosehip (Rosa canina L.); (ii) to optimize the extraction conditions of black rosehip (poly)phenols by means of green methods, in particular pressurized hot water extraction and ethanol modified supercritical carbon dioxide extraction; (iii) to evaluate the effects of extraction methods on bioaccessibility and bioavailability of (poly)phenols using combined in vitro gastrointestinal digestion/Caco-2 cell culture model; (iv) to improve processing and digestive stability of hydrophilic and lipophilic (poly)phenols with high antioxidant acitivity by converting them into edible and stable form for functional foods by means of encapsulation and to investigate the effects of liposomal encapsulation and spray drying processing on bioaccessibility and bioavailability of (poly)phenols using combined in vitro gastrointestinal digestion/Caco-2 cell culture model. The first chapter was designed to characterize Rosa pimpinellifolia fruits collected from Gümüşhane Province in the Black Sea region of Turkey by means of (poly)phenol composition, in vitro antioxidant activity and other biological activities in comparison to commonly consumed rosehip specie. The angiotensin-converting enzyme inhibition potential of black rosehip was also assessed by spectrophotometric assay. Since rosehip (Rosa canina) fruit has traditionally been widely consumed in the form of herbal tea, tea-type infusions of both Rosa species were prepared to reveal the consumption potential of black rosehip. In this context, tea-type infusions and aqueous methanol (80%, v/v) extracts were analyzed by LC-MS/MS in both rosehip species studying different parts of the fruits; whole fruit, flesh, and seed. Apart from other rosehip species, Rosa pimpinellifolia has its dark purplish-black color due to its rich anthocyanin content. Unsurprisingly, any anthocyanin was absent in Rosa canina fruit. Chromatographic analysis showed that (poly)phenol contents varied between rosehip species and drying method applied (freeze drying and air drying). Gallic acid, catechin, protocatechuic acid, procyanidin-B2, procyanidin oligomers and quercetin acid derivatives were principal in both rosehip species. For black rosehip, high level of anthocyanins, (poly)phenols content and high antiradical scavenging capacity were characteristic. Reactive oxygen species (ROS)-induced-DNA damage has been linked to the onset of many degenerative and cardiovascular diseases. Polyphenolic compounds protect cells against the harmful effects of ROS in various mechanisms. Flavonoids and phenolic acids fractions of Rosa canina have been reported to inhibit cell proliferation, however no study exist regarding the antiproliferative properties of black rosehip to the best of our knowlege. In that sense, cytotoxicity by MTT assay, ROS generation, and apoptotic effects by Acridine orange assay in breast cancer cells were evaluated in tea-type infusions and hydroalcoholic extracts from both species. Response surface methodology was adopted to achieve an effective extraction procedure of (poly)phenols from black rosehip (Rosa pimpinellifolia) fruits. Pressurized hot water extraction and ethanol modified supercritical carbon dioxide extraction techniques were investigated by screening parameters including temperature, pressure, solvent composition, and solvent-to-solid ratio. Ultrasound assisted solvent extraction was also assessed. Simultaneous maximization in terms of extraction yield, total antioxidant capacity, total (poly)phenol content, catechin content, total monomeric anthocyanin content, and cyanidin-3-O-glucoside content was performed. Antioxidant activity was evaluated using 2,2-diphenyl-1- picrylhydrazyl radical (DPPH) radical scavenging activity and cupric ion reducing antioxidant capacity (CUPRAC) assays. The experimental data was subjected to the regression analysis to obtain second-order polynomial equations and the fitted polynomial equations are presented as contour plots also showing the linear and quadratic effects of the tested dependent variables. The optimum conditions for extraction was compared to the predicted values of RSM using an independent sample t-test. The optimized conditions were as follows: 75 °C with 10 mL g-1 solvent-to solid ratio under 100 bar during 60 mins, and 60 °C with 25 % aqueous ethanol under 280 bar during 60 mins for pressurized hot water extraction and ethanol modified supercritical carbon dioxide extraction, respectively. When these extracts were examined in terms of bioaccessibility and epithelial cells (Caco-2) uptake upon gastric and intestinal digestion in vitro, all extracts exhibited lower levels of total phenolic content compared to their undigested counterparts (p < 0.05). Chapter 4 aimed to achieve the encapsulation of black rosehip extracts obtained via green techniques applied in previous chapter and to evaluate their antioxidant properties as well as processing and digestive stability. The black rosehip extract (BRE) which was obtained at optimized pressurized hot water extraction conditions, was further encapsulated in biopolymer-coated liposomes and spray dried using maltodextrin as carrier. Being readily available natural biopolymers, chitosan and whey protein were used in coating of liposomes via electrostatic deposition method. In the literature, these biopolymers have been widely used for encapsulation purposes of various polyphenolic extracts. However, in the present thesis, for the first time a comparison between these materials for their efficiency to fabricate stable antioxidant powders. Nanosized particle diameters were achieved by 5 cycle microfluidization of the liposomal dispersions. During spray drying process, total phenolic content (TPC) in extracts decreased due to oxygen and heat exposure. However, the retention efficiency of TPC in biopolymer coated liposomal powders was found significantly higher than spray dried BRE. In a similar pattern as observed with retention of phenolics, retention of antioxidant capacity of the powders was confirmed with CUPRAC assay. In addition, encapsulation provided remarkable protection of the phenolics under in vitro gastrointestinal digestion conditions, resulting in up to a 5.6- fold more phenolics in the bioaccessible fraction, which also had 2.9–8.6-fold higher antioxidant activity compared to the non-encapsulated BRE. Similar results were obtained for encapsulated RPFE using ethanol injection method in preparation of liposomes. Besides, as an alternative colloidal delivery system to liposomes, solid lipid nanoparticles (SLN) were prepared using plant saponin glycyrrhizin to ensure stabilization at low concentrations which has great importance for the food, nutraceutical and pharmaceutical industries. For the first time a series of glycyrrhizin emulsified tristearin SLNs were successfully fabricated and physical stability was determined during 21 days of storage. The influence of glycyrrhizin on the physical stability and crystallization behavior of SLNs were evaluated by dynamic and static lights scattering, electrophoretic light scattering, optical microscopy, visual observations, and differential scanning calorimetry. The SLN formulations containing lower amount of surfactant revealed poor stability against aggregation as clearly observed by optical microscopy. Beyond bioaccessibility, the absorption of (poly)phenols through the intestinal epithelial layer is an important factor in functional food development. Thus, the behavior of individual phenolic compounds loaded in dried liposomes should be investigated to gain insight regarding their bioavailability and resulting bioactivity. In the last chapter, the co-encapsulation of phenolic compounds into nanoliposomes in combination was explored in terms of particle characterization and bioavailability compared to their native (non-encapsulated) form. Phenolic compounds representing berry matrix (catechin, epicatechin, ferulic acid, and resveratrol) were loaded into chitosan- and whey protein-coated liposomal powders. For control purposes, the phenolic compounds were also spray dried without liposomes to observe the effect of liposomal encapsulation on protection of bioactive molecules against processing or digestive conditions. The digestive fate of the samples was determined using in vitro digestion coupled with Caco-2 cell monolayer model. The phenolic compounds, both in encapsulated or free form, decreased upon simulated gastrointestinal digestion, except cis-resveratrol possibly due to trans-to-cis isomerization that occurs during in vitro digestion. Significantly higher digestive stability, solubility, micellization efficiency, and bioaccessibility were found in encapsulated phenolic compounds (p < 0.05). On the contrary, whey protein coated liposomal formulation resulted in substantial increase in the cellular uptake of trans-resveratrol in comparison to other encapsulated formulations or in native form (p < 0.05). The epithelial permeation of the native and encapsulated micellar phenolics were further evaluated in Caco-2 transwell model system. Moreover, all digested formulations was analyzed in terms of fatty acid induced lipid accumulation in human hepatic cancer (HepG2) cells as an indicator of the effect of encapsulation on the potential biological activity.
Valorization of black chokeberry waste as a potential source of bioactive compounds: Their identification, microencapsulation and impact on the human gut microbiota

(Graduate School, 2022-12-07) Çatalkaya, Gizem ; Çapanoğlu Güven, Esra ; 506152502 ; Food Engineering

Epidemiological studies have suggested that adopting a diet rich in fruits and vegetables has been associated with a reduced risk of noncommunicable diseases, such as cardiovascular diseases, neurodegenerative diseases, type II diabetes and cancer. The presence of bioactive substances such as polyphenols has been linked to these potentially health promoting benefits. Polyphenols are secondary metabolites that determine the sensory and nutritional qualities of fruits and vegetables. However, polyphenols are processed as xenobiotics by the human body after consumption, hence the bioavailability of native substances is rather low. Only 5-10% of total dietary polyphenols, mostly those with monomeric and dimeric structures, are estimated to be directly absorbed in the small intestine. The remaining polyphenols pass to the colon, where they are further metabolized by the enzymatic activity of colonic bacteria to molecules with varied physiological significance. These phenolic compounds generated by the microbial catabolism are more absorbable than the original molecules present in foods and may have higher health benefits. In addition to this, dietary polyphenols reaching to the colon can act as prebiotics and they may modulate the gut microbiota by promoting the growth of beneficial bacteria and/or hindering the proliferation of harmful bacteria. Black chokeberry (Aronia melanocarpa) is one of the richest sources of phenolic compounds, especially anthocyanins, among the other berry types. In addition to the anthocyanins, they are a rich source of proanthocyanidins with a high degree of polymerisation. However, despite their health beneficial properties, they are seldomly ingested as fresh due to their distinct astringent flavor, which is perceived as undesirable by the consumers. For this reason, they are processed into juices, jams, etc. Juice processing generates by-products, such as pulp, that might be used in the production of natural colorant and the isolation of the natural nutraceuticals. Although anthocyanins possess potential health-promoting properties and are regarded as promising natural food colorants, unfortunately their unstable nature acts as an obstacle in their practical applications due to their poor bioavailability and susceptibility against environmental factors such as temperature, light, oxygen, pH change, etc. Therefore, encapsulation of these substances might be a suitable method to increase concentrations of bioactive anthocyanins in the gastrointestinal tract and thus boost their beneficial effects. In this useful system, anthocyanins are protected from degradation and prevented from premature color development. Taking all the above-mentioned information into account, this thesis was organized to (i) characterize the polyphenol content of the black chokeberry pulp, (ii) determine the most effective conditions and materials for the encapsulation of the anthocyanin-rich extract obtained from black chokeberry pulp, (iii) determine the effect of black chokeberry polyphenols in different matrices on the human gut microbiota under in vitro conditions. For this purpose, firstly the state of the art on the polyphenol bioaccessibility, bioavailability, interaction with the gut microbiota and analysis through omics approach was comprehensively reviewed and discussed in Chapter 2. In Chapter 3 the extract obtained from the black chokeberry pulp was characterised by both spectrophotometric methods and chromatographic methods. Total polyphenol and total anthocyanin contents of the extract were determined by Folin-Ciocalteu and pH differential methods, respectively. Also, the individual polyphenol composition of the extract was identified by using UPLC-ESI-QqQ-MS/MS method. Dry matter content of pulp was 35.6±0.2%, brix value of the extract was 20% and total anthocyanin content and total phenolic content of extract were determined as 4.91±0.297 mg cyanidin-3-glucoside/mL, 11.5±0.14 mg gallic acid equivalent/mL, respectively. According to LC-MS/MS analysis, ~72% of the total quantified polyphenols consisted of anthocyanins. It is widely known that black chokeberries contain four major anthocyanins, namely cyanidin-3-O-galactoside, cyanidin-3-O-glucoside, cyanidin-3-O-arabinoside, and cyanidin-3-O-xyloside. In this study, cyanidin-3-O-glucoside was identified and quantified. However, apart from the major anthocyanins some other anthocyanins were also detected (cyanidin-3,5-diglucoside, cyanidin-3-O-rutinoside, and pelargonidin-3-O-glucoside). In fact, to the best of our knowledge pelargonidin-3-O-glucoside was identified in black chokeberries for the first time. After characterizing the extract, the second goal of this study was to encapsulate the black chokeberry extract with different coating materials by using spray drying technique which was also detailed in Chapter 3. Among the encapsulation techniques, the spray drying method has been largely utilized for drying heat-labile nutraceuticals since it is precise, efficient, simple and cost-efficient in the processes. The selection of coating material to entrap the active material by spray drying is crucial to achieve an efficient encapsulation. Therefore, five different coating materials have been tested for the microencapsulation of black chokeberry extract (maltodextrin with dextrose equivalent of 6, maltodextrin with dextrose equivalent of 20, its blends with gum Arabic, xanthan gum or whey protein isolate). Spray drying conditions were chosen as follows: inlet temperature of 150 °C, the outlet temperature of 90 °C, 4.5 mL/min feed flow rate, 0.357 m3/h air flow rate, and an aspirator capacity of 100%. For the determination of the most effective system, physicochemical characteristics of the powders such as moisture content, particle size, capsule morphology, color, spray drying yield, encapsulation efficiency, total anthocyanin content, total and individual phenolic content, and total antioxidant activity were investigated. Within the five different wall materials, maltodextrin:gum Arabic provided the maximum encapsulation efficiency (71.5%) while MD6 resulted in the lowest encapsulation efficiency (38.3%). The spray-dried powders presented low moisture content in an acceptable range from 2.57 to 3.27%. Also, spray drying yield varied between 51.4 to 78.1%. The addition of gums or protein significantly enhanced both total phenolic content and total antioxidant capacity. The highest increase in total phenolic content was observed when gum Arabic was used along with maltodextrin as a coating material. Although significantly different results were obtained for most of the parameters tested for each wall material, all of them resulted in successful microencapsulation of black chokeberry pomace extract. However, within the tested wall materials, the maltodextrin:gum Arabic combination had better results compared to the other wall materials. For this reason, the next step of the study was continued with the spray-dried powders obtained by using maltodextrin: gum Arabic as a wall material. The effect of black chokeberry phenolics on the human gut microbiota in a sophisticated, computer-controlled dynamic colonic fermentation model (TIM-2) was investigated in Chapter 4. For this purpose, black chokeberry pomace as juice processing by-product, anthocyanin rich extract from black chokeberry pomace, and microencapsulated extract in maltodextrin-gum Arabic system were examined in terms of the changes in microbial composition, short-chain fatty acid (SCFA) and branched-chain fatty acid (BCFA) contents. Stool samples were collected from 5 healthy donors to prepare a standardized microbiota cocktail. The experiments in TIM-2 were last for 40h where the first 16h was adaptation period of the human fecal microbiota and the last 24h was the test period. Samples were collected from lumen and dial compartments at time 0h and 24h. Genomic DNA from the luminal samples was extracted and sequencing by polymerase chain reaction (PCR) amplification of the 16S rRNA gene V3-V4 region was carried out by using Illumina MiSeq and BCL2FASTQ pipeline. The QIIME2 (Quantitative Insights Into Microbial Ecology) software package was employed for taking sequencing data from raw sequences to interpretation for the microbiota analyses. The statistical analyses were done in RStudio. The abundances of microbial species in the total microbial community were calculated and shown as relative abundance (RA). According to the results, the fermentation of black chokeberry polyphenols in the in vitro colon model (TIM-2) resulted in shifts in the standardized microbiota and differentiation in the extent of the production of SCFA and BCFAs. Synergy between maltodextrin+gum Arabic+polyphenols resulted in an increase in the relative abundances of some health-promoting taxa (Anaerostipes, Blautia, Christensenellaceae R7 group, Prevotella 9) and decrease in the disease related taxa Alistipes. Encapsulation increased the SCFA production and decreased the BCFA production in the lumen. Nevertheless, none of the metabolites could be correlated with the identified operational taxonomic units. In the final chapter (Chapter 5), overall evaluation of the results obtained throughout this study, conclusions, and recommendations for the future research were presented. The main outcomes of this study revealed that pulp obtained from Turkish black chokeberries has a unique polyphenol profile with bioactive properties. The successful microencapsulation of polyphenols extracted from black chokeberry pulp can be used as a value-added natural colorant in powder form with bioactive properties in food, pharmaceutics or cosmetic product formulations. Also, clack chokeberry polyphenols present in the extract, pulp or encapsulate have the potential to be used for establishing a healthier gut as it caused a shift in the gut microbial composition and SCFA levels in a good way.

Gözat

Çıkarma tarihi ile LEE- Gıda Mühendisliği Lisansüstü Programı'a göz atma

Sayfa başına sonuç

Sıralama Seçenekleri