45C-10 |
Effect of chlorophyll content and temperature on the production of volatile compounds in soybean oil exposed to light |
J. M. BOFF and D. B. Min. Dept. of Food Science & Technology, Ohio State Univ., 2015 Fyffe Ct., 110 Parker Food Science Bldg., Columbus, OH 43210-1007 Light exposure has adverse effects on the quality of soybean oil. Upon exposure to light, chlorophyll present in soybean oil can produce singlet oxygen, which may accelerate oil oxidation resulting in the production of volatile compounds in greater amounts than that achieved by radical-mediated oxidation. Pentane, 2-heptenal, and 2,4-heptadienal may be formed as primary products of singlet oxygen oxidation of fatty acids contributing to the off-flavor of soybean oil. The objective of this research was to determine the effect of chlorophyll content and temperature on the production of volatile compounds in soybean oil. Soybean oil containing 0, 1, 5 or 10ppm added chlorophyll was exposed to an incandescent light at 4, 20, 32 or 40C for 10 days. A control sample containing 0ppm added chlorophyll was kept in the dark for 10 days at each temperature. Headspace volatiles were collected by SPME using a PDMS/DVB fiber and analyzed by GC-MS. Approximately half of the quantified volatile compounds were significantly dependent on the amount of chlorophyll in the oil. When exposed to light, soybean oil containing 10ppm chlorophyll produced 2 to 10 times as much pentane, 2-heptenal, 2,4-heptadienal, pentanal, 1-pentanol, and 2-octene as the oil containing 0ppm added chlorophyll. Storage at 32C or 4C typically resulted in the production of 2 to 10 times greater amounts of volatiles than were produced at 4C. Production of chlorophyll-sensitive compounds at 40C in oil containing 10ppm chlorophyll was 5 to 100 times greater than that produced in oil containing 0ppm chlorophyll stored at 4C. The amount of chlorophyll present in soybean oil significantly increased the production of many, but not all volatile compounds. A reaction mechanism other than radical-mediated oxidation, such as the singlet oxygen pathway, could be contributing to the production of chlorophyll-sensitive compounds. Increasing temperatures significantly enhanced the production of chlorophyll-sensitive compounds.
Session 45C, Food Chemistry: Flavor and aroma chemistry
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