Autoxidation of stored soybean lecithin

Abstract

Soybean phospholipid concentrates, generally called lecithins, can he stored for long time in a refrigerator or even at room temperature, without apparent changes of sensory properties, and their peroxide value usually remains low. This behaviour is related to the antioxidant activity of phospholipids in refined vegetable oils [ 11 which was attributed to their synergistic effect in presence of tocopherols [2, 31. Both the low peroxide content and the inhibitory activity may be explained, at least partially, by the hydroperoxide decomposing activity of phospholipids [4], the rate of hydroperoxide decomposition King proportinal to the square root of the hydroperoxide content 151. Therefore, we have analysed several samples of lecithin to find out whether the presence of phospholipids only affects the rate of hydroperoxide accumulation or the formation of total oxidation products, respectively.

Modification of lecithin by physical, chemical and enzymatic methods

“…Since these lipids contain phosphorous and a nitrogen-containing component such as choline and unsaturated fatty acids, they offer a system far more complicated for oxidation than the neutral triacylglycerols. The primary products of the autoxidation of unsaturated fatty acids in phospholipids are hydroperoxides and alkyl peroxides, and finally aldehydes and ketones are formed [51,52]. The amount of oxidation can be assessed by oxygen uptake measurements in emulsified systems.…”