Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Hubei Key Laboratory of Oilcrops Lipid Chemistry and Nutrition, Wuhan, China.
Ultrason Sonochem. 2012 Sep;19(5):1015-20. doi: 10.1016/j.ultsonch.2012.02.004. Epub 2012 Feb 18.
This study is focused on the enzymatic esterification of phytosterols with different acyl donors to produce the corresponding phytosterol esters catalyzed by Canadia sp. 99-125 lipase under ultrasound irradiation. An ultrasonic frequency of 35 kHz, power of 200 W and time of 1h was determined to guarantee satisfactory degree of esterification and lipase activity. The influence of temperature, substrates concentration and molar ratio was investigated subsequently. The optimum production was achieved in isooctane system at 60°C with phytosterol concentration of 150 μmol/mL and phytosterol to fatty acid molar ratio of 1:1.5, resulting in a phytosterol esters conversion of above 85.7% in short reaction time (8h). Phytosterols esters could also be converted in high yields to the corresponding long-chain acyl esters via transesterification with triacylglycerols (above 90.3%) under ultrasound irradiation. In optimum conditions, the overall esterification reaction rate using the ultrasonic pretreatment process was above 2-fold than that of mechanical stirring process without damage the lipase activity.
本研究聚焦于加拿大假丝酵母脂肪酶（Canadia sp. 99-125）超声辐射下，利用不同酰基供体对植物甾醇进行酶法酯化生成相应植物甾醇酯。确定超声频率 35 kHz、功率 200 W、时间 1 h 可保证令人满意的酯化度和脂肪酶活性。随后考察了温度、底物浓度和摩尔比对酯化反应的影响。在正辛烷体系中，于 60°C 时，当植物甾醇浓度为 150 μmol/mL，植物甾醇与脂肪酸摩尔比为 1:1.5 时，可在短反应时间（8 h）内获得 85.7%以上的植物甾醇酯转化率，实现最佳生产。甾醇酯在超声辐射下也可通过与三酰基甘油（＞90.3%）进行转酯化反应，以高收率转化为相应的长链酰基酯。在最佳条件下，与机械搅拌过程相比，超声预处理过程的整体酯化反应速率提高了 2 倍以上，且不会损害脂肪酶活性。
