Abstract
Triacylglycerols (TAGs) containing conjugated linolenic acid (CLN) lack oxidative stability. In general, the oxidative stability of oils and fats depends on their fatty acid composition, and when the fatty acid composition is equal, the TAG molecular species has a decisive influence on oxidative stability. In the present study, structured oils containing 24% or 45% CLN were prepared by introducing CLN into oleic acid-rich TAG by enzymatic transacylation, and mixed oils containing 24% or 45% CLN were prepared by mixing oleic acid-rich TAG and Tung oil. The influence of TAG molecular species on the oxidative stability of the TAGs containing CLN was evaluated by comparing the oxidation stabilities of the TAGs. The molecular species of the TAGs containing CLN were analyzed by HPLC, and this revealed that TAG consisting of three molecules of CLN (3CLN-TAG), was present in the mixed oils, while TAG consisting of one or two molecules of CLN was present in the structured oils. In addition, the results of autoxidation and heating oxidation tests indicated no difference in the oxidative behavior of TAG between the structured oil and the mixed oil containing 24% CLN. However, the structured oil containing about 45% CLN showed an obviously high oxidative stability in comparison with mixed oil containing about 45% CLN. These results indicate that structured oils lacking 3CLN-TAG are more stable against oxidation.
