Determination of the extent of oxidation of fats

Summary The amount of secondary oxidation products in refined and unrefined fats has been determined by reaction with benzidine acetate in iso-octane absolute alcohol solution, and measurement of the absorption at 350 mμ of the yellow color has been made. An “aldehyde value” has been calculated from this absorption intensity, using cinnamaldehyde as a reference substance. Determination of the aldehyde value and peroxide number of oils before and during refining has given information on the effect of the different refining processes on the state of oxidation of the oils. The effect of hardening on the content of oxidation products of an oil has been investigated. The effect of the amount of oxidation products in the unrefined material on the flavor stability of the refined material and of the margarine made from it has also been studied.