Oxidation Behavior of Triacylglycerol Containing Conjugated Linolenic Acids in sn-1(3) or sn-2 Position

The location of unsaturated fatty acid in triacylglycerols (TAGs) affects their oxidative stability. Herein, we studied the effect of location of conjugated linolenic acids (CLNs) in TAGs on their oxidative stability. First, the TAGs containing CLNs at sn-1(3) and sn-2 positions, were enzymatically prepared via Lipozyme RM-IM (immobilized Rhizonzucor zniehei lipase)-mediated acidolysis- and contained ca. 60% of CLNs at sn-1(3) or sn-2 position. The auto-oxidation test at 30 degrees C in the dark showed oxidative stability of TAGs that mainly contained CLNs at sn-2 position was higher than that at sn-1(3) position based on peroxide value, anisidine value, polymeric substance and polar compound contents. Moreover, the thermal-oxidation test at 90 degrees C for 24 h, showed the same result. Furthermore, even after 24 h of thermal oxidation, the oxidative stability of the TAGs containing CLNs at sn-2 positions rather than sn-1(3) positions remained at a higher level. Thus, the results showed that the TAG-containing CLNs are stable when the CLNs are located at sn-2 positions.