45C-25 |
Photooxidation of tomato juice volatiles |
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 Absorption of fluorescent light by chlorophyll can lead to the formation of singlet oxygen. Commercially-available tomato juice is exposed to fluorescent light during its shelf-life. This exposure may increase total volatile compounds and alter the flavor profile of stored tomato juice. The objective was to determine effects of light on total volatile compounds and relative abundance of important flavor compounds in stored tomato juice. Five grams of tomato juice was transferred to 20 ml vials. Vials were placed in a box with a fluorescent light source for 0, 6, 12, 24, 48, and 96 hrs. Volatile compounds were collected using a SPME fiber (75µm Carboxen/Polydimethylsiloxane). Quantification and identification of volatile compounds was determined by HP GC 6890 and HP GC-MS 5890. The results show that exposure to flourescent light increases total volatile compounds in tomato juice. The total electronic counts of the tomato juice control was initially 2.8 x 10^6 and ca 3.0 x 10^6 total electronic counts throughout storage. Volatiles in light-exposed juice increased from 2.8 x 10^6 initially.to 7.0 x 10^6 at 96 hrs. Pentanal, heptanal, and octenal were detectable in light-exposed samples, but not in dark samples. The coefficient of variation of SPME for tomato juice volatile compounds was 3%. Total volatile compounds in light-exposed tomato juice samples increased with storage time. The detection of compounds in light-exposed juice suggests that singlet oxygen oxidation may be responsible for the formation of pentanal, 2-heptanal, and 2-octenal. Formation of these volatile compounds may have positive or negative effects on flavor quality.
Session 45C, Food Chemistry: Flavor and aroma chemistry
|