Lipase-catalyzed production of phytosteryl esters and their crystallization behavior in corn oil

摘要

Plant sterol esters have been shown to have beneficial effects on plasma cholesterol level and have recently used as functional food ingredients. Conjugated linoleic acid (CLA) has several health benefits and medium chain fatty acids (MCFAs) can be used as a rapid energy source for human. In this study, we produced the sitosteryl esters from CLA and MCFAs using various lipases as a bio-catalyst. Among lipases, AYS (from Candida rugosa) was the most effective for the synthesis of sitosteryl esters in the presence of either water (maximum 26.8%) or hexane (maximum 28.3%) during a 48 h reaction. Generally, the crystallization temperature of MCFA steryl esters increased with the carbon numbers of the acyl moiety, indicating that sitosteryl laurate had the highest crystallization temperature among the produced steryl esters with MCFAs. The cooling thermogram of corn oil containing 2.5%> (w/w) of sitosteryl laurate was similar to that of original oil, suggesting that sitosteryl laurate does not crystallize independently in vegetable oil (i.e., corn oil) at concentrations below 2.5%.