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ÖgePhenolic 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 MühendisliğiTomatoes, 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.