OXIDATIVE STABILITY OF PURIFIED CANOLA OIL TRIACYLGLYCEROLS WITH ALTERED FATTY-ACID COMPOSITIONS AS AFFECTED BY TRIACYLGLYCEROL COMPOSITIONAND STRUCTURE

Canola oil triacylglycerols from genetically modified canola lines (In terMountain Canola Co., Cinnaminson, NJ) have been evaluated for their photooxidative and autoxidative stabilities, as influenced by their f atty acid compositions and their triacylglycerol compositions and stru ctures. Purified canola oil triacylglycerols were oxidized in duplicat e in fluorescent light at 25 degrees C and in the dark at 60 degrees C under oxygen, and their oxidative deterioration with time was monitor ed by determining colorimetric peroxide values. Also monitored with ti me, oxidation products were determined by reversed-phase high-performa nce liquid chromatography with ultraviolet absorbance detection. Total volatiles, generated by thermal decomposition of the oxidized triacyl glycerols, were quantitated by static-headspace gas chromatography. Th ese experimental parameters were statistically correlated with predict ed oxidizability, fatty acid composition, position of fatty acids on g lycerol carbons and triacylglycerol composition. Oxidative deteriorati on of canola triacylglycerols correlated negative ly with oleic acid c omposition, with oleic acid content at carbon 2 and with trioleoylglyc erol content of the oil. Deterioration was positively correlated with the amount of linolenic acid on nonspecific locations on glycerol carb ons 1,2 and 3, the amount of linoleic acid on glycerol carbon 2 and wi th sn-oleoyllinoleoyllinolenoyl glycerol content. Differences in chara cter or quantity of volatile product and triacylglycerol hydroperoxide s mere low, whether generated during autoxidation or photooxidation of the canola triacylglycerols.