Novel process for enzymatic production of sterol esters in microaqueous solution with cholesterol esterase from Trichoderma sp. AS59

Phytosterols, their structure are very similar to that of cholesterol, have promise as a functional food material. However, they have not been actively used as material for low solubility in both oil and water. The research objective is to increase the solubility by modifying the sterol using microbial enzymes and to broaden the reach of phytosterols as biomass material and a food additive in our laboratory. We recently reported the characterization of novel cholesterol esterase from Trichoderma sp. AS59 isolated from soil. Therefore, in the present study, we examined the ability of the enzyme to synthesize steryl esters from sterol and free fatty acids of varying chain lengths. As a result, all the mediumand long-chain free fatty acids used are successfully employed in cholesterol ester synthesis and the yield of cholesteryl palmitate reached over 60% in large scale such as 30 mL of solvent. Of additional interest is that the fatty acid specificities in the synthesis and hydrolysis of cholesteryl esters were entirely different from each other. Furthermore, we attempted to synthesize stigmasteryl palmitate as a food additive and found that the enzyme catalyzed the synthesis of the ester. That indicates the potential utility of the enzyme in the food industry.