Oxidative and flavor stability of oil from lipoxygenase-free soybeans

Oxidative and flavor stability of oil from lipoxygenase-free soybeans

1998

REP.SB-1311

Soybeans that lack or contain three lipoxygenase (LOX) isozymes, LOX-1, LOX-2, and LOX-3, were evaluated for oxidative and flavor stability at 60 degree C in the dark and at 35 degree C in the light. Although the two types of soybeans had a similar genetic background, there were significant differences (P <= 0.01) in fatty acid percentages between the lipoxygenase-free and normal oils before and after storage at both temperatures. The linolenic acid content of oil from LOX-free germplasm before storage averaged 7.2%, while normal lines averaged 6.6%. The linoleic acid content after storage averaged 6.9% for LOX-free and 6.6% for normal oils. LOX-free oil was not significantly different from normal oil in flavor, as judged by a sensory panel, or in concentrations of volatiles during storage at eigher storage condition. LOX-free oil had less hexanal than normal oil before storage, but had significantly greater (P <= 0.05) levels after storage for two weeks at 35 degree C. Peroxide values of oil from LOX-free soybeans were significantly greater (P <= 0.01) than oil from the normal soybean after storage at 60 and 35 degree C. LOX-free oil had significantly greater (P <= 0.01) levels of alpha, beta and r-tocopherols. In general, oil from LOX-free soybeans did not have improved flavor or oxidative stability. Differences between the two oil types in peroxide value and in production of a few volatiles were probably a result of the differences in initial fatty acid composition. [AS]

v.75(9):1121-1126, AMERICAN OIL CHEMISTS` SOCIETY, JOURNAL

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