114B-14 |
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S. R. YOO, S. D. Howard, and D. B. Min. Dept. of Food Science & Technology, Ohio State Univ., 2015 Fyffe Ct., 110 Parker Food Science Bldg., Columbus, OH 43210-1007 Tomato juice is one of major juices and is gaining popularity due to the nutritional benefits on prostate cancer, heart disease, and degenerative eye disease. However, high flavor quality tomato juice is needed to meet the demands of consumers. Objectives are to develop a simple and rapid flavor analysis method, to study the relationship between headspace oxygen and volatile compound formation, and to develop the chemical mechanisms for important volatile compounds formations. Five mL of tomato juice were transferred into 20 ML serum bottles, which were air tightly sealed with Teflon septa and Aluminum caps. Samples were stored under light and in dark at 4 and 30им C. Headspace oxygen and volatile compounds were analyzed by gas chromatography with thermal conductivity and flame ionization detectors, respectively. The volatile compounds were analyzed solid phase microextraction using carboxen / polydimethylsiloxane. A hedonic scale of 1 to 9 was used to evaluate the sensory qualities of tomato juices. Coefficients of variations for headspace oxygen and volatile compound analyses were 1.5 and 4.2 %, respectively. As the headspace oxygen decreased, the volatile compounds increased with R2=0.97. Light has major effects on the volatile compounds formation and the flavor qualities of tomato juices. Dimethyl disulfide increased under light and was formed by singlet oxygen and methionine. Singlet oxygen was formed from triplet oxygen by chlorophyll under light. The formation of 2-isobuthylthiazole and benzaldehye increases steadily as the headspace oxygen decreases during storage and depends on the oxygen content. Chemical mechanisms for the formations of 2-isobuthylthiazole from cystein, and benzaldehye from fatty acid are developed. As the headspace oxygen is decreased, the formation rated of 2-isobutylthiazole and benzaldehyde decreased. The high flavor quality tomato juice can be maintained by minimizing the oxidation, understating, and measuring the formation of desirable and undesirable flavor compounds during processing and storage.
Session 114B, Food Chemistry: Flavor chemistry
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