LEE- Gıda Mühendisliği-Yüksek Lisans

Bu koleksiyon için kalıcı URI

http://hdl.handle.net/11527/19293

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Yazar "Güneş, Gürbüz" ile LEE- Gıda Mühendisliği-Yüksek Lisans'a göz atma
  • Öge
    Farklı gaz geçirgenliklerine sahip ambalaj malzemelerinin toz formda ezogelin ve şehriyeli tavuk çorbalarının kalitesi ve raf ömrü üzerine etkileri
    (Lisansüstü Eğitim Enstitüsü, 2023-02-01) Cellat, Ayşe Merve ; Güneş, Gürbüz ; 506191502 ; Gıda Mühendisliği
    Son zamanlarda tüketicilerde hazır gıdaya ilgi gün geçtikçe artmaktadır. Hazır toz çorbalar da bu ürünlerden biridir. Kolay taşınabilir ve pişirme açısında zaman kolaylığı sağlaması bu gıda ürünlerinin en önemli avantajlarındandır. Hazır çorba, kurutulmuş bileşenleri içermekte olup, su aktivitesi 0,60 değerinin altında olması sebebiyle dayanıklı gıda sınıfına girmektedir. Bu sebeple genel olarak mikrobiyal bozulma tehlikesi oldukça düşüktür. Bunun yanı sıra bu gıda ürünlerinde kimyasal bozulmalar meydana gelmekte olup bunların içinde en önemli yeri yağ oksidasyonu almaktadır. Hazır çorbalar kurutma prosesinden geçirilen ürünler olup bozulmalara karşı oldukça dayanıklı ürünler olmasına karşın doğru ambalaj materyali seçmek gıdanın raf ömrünü ve maliyetini önemli ölçüde etkilemektedir. Ambalaj materyalinin geçirgenliği gıda ile çevre arasında madde geçişini dolayısıyla gıdanın raf ömrünü önemli şekilde etkilemektedir. Çalışmanın amacı farklı oksijen geçirgenilk özelliğine sahip üç farklı ambalaj materyalinin (1,3-17,1 arasında), hazır çorba ürünlerinin raf ömrüne etkisini araştırmaktır. Bu çalışmada farklı geçirgenlik özelliğne sahip üç farklı ambalaj materyali kullanılmıştır. Bu materyaller Ambalaj-1, Ambalaj-2 ve Ambalaj-3 olarak kodlanmış olup oksijen geçirgenliği sırasıyla 1.31, 17.07, 4.79 cm3/m2.gün'dür. Ambalajların su buharı geçirgenliğ oldukça birbirine yakın olup sırasıyla 2,29, 1,45 ve 1,81 g/m2.gün'dür. Çalışmada test ürünü olarak ezogelin çorbası ve şehriyeli tavuk çorbası ürünleri kullanılmıştır. Bir ticari firmanın kendi tesisinde dolum yapılan ve test ambalaj materyalleri ile normal atmosfer gazı altında ambalajlanan ürünler fakülteye getirilmiş olup farklı depolama koşullarında depolanmıştır. -15℃ depolama sıcaklığı taze kontrol örneklerini oluşturmakta olup, 25℃ depolama sıcaklığı ticari depo sıcaklığı ve 35 ℃'de depolanan örnekler ise hızlandırılmış test koşullarını temsil etmektedir. Ayrı ayrı gruplandırılıp, belirtilen şartlarda depolanan numuneler her 2 ayda bir çeşitli kalite özellikleri açısından analiz edilmiştir. Bunlar tepe boşluğu gaz analizi, renk analizi, nem analizi, oksidasyon için TBARS analizi ve duyusal analizdir. Çalışmada sonuç olarak Ambalaj-1 ve Ambalaj-3 ile ambalajlanan numunelerde tepe boşluğundaki oksijen oranı zaman içinde azalmış olup, karbon dioksit oranı artmıştır. Ambalaj-2 ile depolanan numunelerde ambalaj içi gaz konsantrasyonu önemli şekilde değişmemiştir.Ambalaj-1 ile depolanan ezogelin çorbası numuneleri rengini daha iyi muhafaza etmiştir. Şehriyeli tavuk çorbası numunelerinde zaman içinde renkte koyulaşma görülmüştür. Hem ezogelin hem de şehriyeli tavuk çorbası numunelerinde nem içeriği, TBARS değeri ve duyusal özellikler önemli şekilde etkilenmemiştir. Sonuç olarak yapılan analiz ve gözlemler ile 12 aylık depolama süresi içerisinde ambalaj materyalinin geçirgenliğinin 1,3 ve 17, 1 aralığında, test edilen ezogelin ve şehriyeli tavuk toz çorbası örneklerine etkisi önemli bulunmamıştır.
  • Öge
    Microbial decontamination of food packaging films using corona non-thermal plasma
    (Graduate School, 2023-07-14) Acar, Emine Gizem ; Güneş, Gürbüz ; 506211510 ; Food Engineering
    Foods are packaged during various processes, especially transportation and storage, during the "from farm to fork" period. Food packaging has four primary purposes: protection, convenience, containment, and communication. Apart from these, packaging has many functions such as extending the shelf life of food and reducing food waste, contributing to sustainability, ensuring the traceability of food, and protecting consumer health. Although foods can be packaged with many packaging materials such as glass, metal and paper, the most widely used material in food packaging today is polymers, in other words, plastics. Polymers are preferred due to their advantages of being easily shaped, have low cost, are light, transparent, and can be easily sealed with temperature. Although packaging materials are barriers that protect food from external factors, when adequate hygienic conditions are not provided, physical, chemical or biological cross-contamination from packaging material to food is possible. Although it varies according to the physicochemical properties of packaging materials and environmental conditions, it has been proven that various microorganisms, including pathogens, can be present on packaging surfaces. In fact, it has been reported that up to 6 log CFU/cm2 total mesophilic aerobic bacteria can be found on the packaging material. Since plastic packaging materials do not have antimicrobial properties, sterilization before contact with food is an obligation to protect consumer health. Today, various physical and chemical methods are applied for the disinfection or sterilization of packaging materials. Major examples of these methods include thermal treatments, irradiation, UV-C, pulsed light, ozone, hydrogen peroxide or the use of other disinfectants. Despite the disadvantages of existing technologies, non-thermal, or cold plasma stands out with its advantages. Plasma, known as the fourth state of matter, is a gas with reactive oxygen and nitrogen species (ROS: O, O2, O3, OH; RNS: NO, NO2 and NOx), UV, free radicals and charged particles. Plasma is obtained by ionizing the gas as a result of applying electrical energy to the gas between two electrodes with a high electrical potential difference. Plasma systems are classified according to the electrode used. Corona discharge is a type of discharge that causes a strong glow extending from the sharp point of the emitter electrode to the collector electrode. Corona discharge cold plasma systems can operate with lower power requirement, at atmospheric pressure, with ambient air, without causing an increase in temperature on the surface. Although cold plasma can also be used to improve the surface properties of packaging films, it is also widely used for microbial decontamination of packaging and surfaces. Although there are facilities that perform sterilization of packaging materials with cold plasma today, it is necessary to increase the application efficiency and reduce the cost in order for the technology to become widespread. In this study, the decontamination efficiency of the custom-made corona discharge non-thermal plasma (NTP) system on commonly used polymeric food packaging materials was investigated. In order to test the inactivation efficiency of the NTP system in a wide range of microorganisms, a test group of microorganisms was formed representing vegetative cells, spore-former bacteria and fungi. Unlike the cold plasma sterilization studies in the literature, how the NTP inactivation efficiency changed as a result of wetting the film surface was investigated. The main aim of wetting the film surface before plasma treatment is to convert H2O into ROS by the effect of plasma, and to obtain higher inactivation rates as a result of exposure of microorganisms to higher concentrations of ROS. In this context, the inactivation efficiency of corona discharge NTP system against Escherichia coli and Bacillus subtilis vegetative cells, B. subtilis spores, Aspergillus niger and Penicillium expansum spores was investigated on three different packaging materials, biaxially oriented polypropylene (bOPP), low density polyethylene (LDPE) and polyethylene terephthalate (PET). Microorganisms were inoculated on the surface of the packaging films by spot inoculation method and the inoculated films were dried to simulate a real contamination. In order to investigate the effect of wet application on the inactivation efficiency, the trials were repeated under the same application conditions, by additionally covering the film surface with a thin layer of water. Bacterial analyses were carried out by pour plate method, fungal analyzes were carried out by spreading plate method. Before the analysis of the inactivation efficiency of cold plasma, it was tested whether the selected microorganisms in the packaging materials remained viable. As a result of all analyzes, it was found that wetting the film surface and increasing the cold plasma exposure time statistically increased the microbial inactivation efficiency of the NTP system (p<0.05). Since inactivation on the surface of each packaging film was analyzed in experiments on different days, the film material was not considered as a variable, and the results were evaluated within themselves. Considering the maximum decontamination amounts determined for each specified application parameter, in dry applications, the detected inactivation rate by NTP system was 2.98 log CFU/film for E. coli in 3 min, 0.93 log CFU/film for vegetative cells of B. subtilis in 3 min, 0.33 log CFU/film for B. subtilis spores in 12 min, 1.34 log CFU/film for A. niger in 12 min and 0.67 log CFU/film for P. expansum in 3 min. Likewise, as a result of covering the surfaces of the contaminated packaging materials with a thin layer of water before plasma application, the inactivation rates were increased to 5.58 log CFU/film for E. coli in 3 min, 1.5 log CFU/film for vegetative cells of B. subtilis in 3 min, 1.05 log CFU/film for B. subtilis spores in 12 min, 1.46 log CFU/film for A. niger in 3 min and 3.20 log CFU/film for P. expansum in 3 min. Considering all the results together, it was observed that wetting the film surface before the cold plasma treatment increased the microbial inactivation efficiency of the corona discharge NTP system statistically in almost all conditions (p<0.05). It has been also noted that the treatment to the wet surface increases the effect up to 3 or even 4 times in some microorganisms compared to the plasma treatment on the dry surface. In this way, it has been seen that it is possible to reach the desired microbial inactivation times in shorter application times with the effect of wetting the surface. It was found out that E. coli was the most sensitive microorganism to the NTP system in both wet and dry applications, while the most resistant microorganism was B. subtilis spores. Considering the average values for all microorganisms, the resistance of microorganisms against the NTP system during dry application can be listed from lowest to highest as E. coli, vegetative B. subtilis cells, P. expansum, A. niger and B. subtilis spores, respectively. On the other hand, in the applications where the film surface was wetted, this order changed as E. coli, P. expansum, A. niger, vegetative B. subtilis cells and B. subtilis spores, respectively. This situation can be interpreted that the mechanism of inactivation of plasma is caused by two main effects; inactivation by ROS formation was more effective in microorganisms other than B. subtilis, while decontamination by UV radiation is more effective in B. subtilis cells. With the findings obtained as a result of the study, it can be said that the NTP system designed and produced within the scope of the project is effective on various microorganisms such as vegetative cells, spores and fungal spores. In addition, the fact that wetting the film surface before plasma application statistically increases the microbial decontamination efficiency of the NTP system under almost all conditions. The designed NTP system works with ambient air at atmospheric pressure. This will reduce the installation and operation cost in the facilities. When all the results are examined, the designed system is promising in terms of savings by increasing the desired effect in less energy and shorter time in polymeric packaging material sterilization.
  • Öge
    The effect of different starch types on texture properties of wafer sheets
    (Graduate School, 2024-06-10) Ünlü Sarı, Gizem ; Güneş, Gürbüz ; 506191510 ; Food Engineering
    Wafer sheets are available in many industrially produced snacks with different formulations. Each manufacturer creates different formulations to obtain the optimum texture for their products and consumers. In this study, different starch types were added to the recipe of wafer sheets at different ratios and their effects on the texture of wafer sheets were investigated. This study focused on investigating how different types and concentrations of starch, specifically potato, wheat, and rice starches at levels of 3%, 6%, and 9%, influence the texture of wafer sheets. At the beginning of the study, characterization analyses were conducted on the starches used. Particle size, water holding capacity, and differential scanning calorimetry analyses were applied to potato, wheat, and rice starches. The results of these analyses were utilized to interpret the effects of starches in wafer sheet recipes. Post-baking moisture content and textural properties of the wafer sheets were examined. Given that the water content in the recipes remained constant, the impact of the starch type and proportion, the sole varying factors, on the residual moisture content after baking was observed. Texture analysis included examination of parameters such as hardness and fracturability. At the beginning of the shelf life, moisture analysis revealed that wafer sheets containing potato starch had significantly higher moisture content compared to those containing wheat or rice starch. As the proportion of potato starch increased, wafer sheets showed progressively higher moisture levels. Also, hardness and fracturability parameters were analyzed for texture analysis. When evaluated in terms of hardness analysis, wafer sheets containing potato starch exhibited statistically significant higher hardness values compared to waffle sheets containing wheat or rice starch, as well as the control samples. Additionally, wafer sheets containing potato, wheat, and rice starches at 3% concentration showed statistically higher hardness values compared to other starch ratios and the control. Among all starch types and ratios examined, potato starch showed the most significant differences in hardness, fracturability, and moisture analyses compared to the control samples. High values in hardness and fracturability indicate that wafers containing potato starch are more brittle. Moreover, recipes containing potato starch exhibited the highest moisture levels both at the beginning and end of shelf life, suggesting that wafer sheets with potato starch require better preservation throughout their shelf life. The properties of wafer sheets may vary according to production efficiencies and textural characteristics preferred by the consumer. There are no appropriate or inappropriate value ranges for the data obtained. In this study, the wafer sheets obtained were compared with each other and their differences were revealed.