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Summary An evaluation of thiobarbituric acid (TBA) as an agent for the measurement of fat oxidation was made by the application of several empirical procedures to animal and vegetable fats. An extraction procedure was used for removing the products of oxidation. The reaction with TBA was conducted in a boiling water bath to produce a red color, which was then estimated spectrophotometrically. Fats stored at −20, 0, 72, and 100°F. (−29, −18, 22, and 38°C.) and fats oxidized by the active oxygen method (A.O.M.) and by ultraviolet irradiation were examined. It was found that the TBA test might be of value in following the course of oxidation of cottonseed oil and soybean oil in the A.O.M. apparatus. Higher TBA values were obtained for soybean oil than cottonseed oil at comparable peroxide values. This is of interest because of the greater tendency of soybean oil to develop oxidized flavors. The volatile reaction products of oxidation were collected in toluene, and a comparison of the TBA values at comparable peroxide values of lard, cottonseed and soybean oils showed that the soybean oil volatiles developed the greatest intensity of color.
Sidwell et al. (Wed,) studied this question.