| ：The aim was to optimize the technological conditions of preparing OPO by transesterification of oleic acid and palm stearate catalyzed by Novozym 40086 enzyme in solvent-free system. Taking OPO content, PPP content and the content of palmitic acid at sn-2 position in all palmitic acid as indicators, the effects of enzyme dosage, substrate molar ratio, reaction time and reaction temperature on the transesterification were investigated by single factor experiment. The reuse times of lipase was studied, and the lipase dosage was determined by calculating the cost of the enzyme. Based on the single factor experiment, the OPO preparation conditions were optimized using response surface methodology. The results showed that the optimal lipase dosage determined by single factor experiment was 6%(on the basis of total substrate mass), which could be reused for 6 times. The optimal OPO preparation conditions were obtained by response surface methodology as follows: dosage of enzyme 6.3%, molar ratio of oleic acid to palm stearate 5.7∶ 1, reaction time 5.2 h, reaction temperature 60 ℃. Under the optimal conditions, the content of OPO, PPP and palmitic acid at sn-2 position in all palmitic acid were 43.13%, 7.65% and 61.28%, respectively, which matched the requirements of GB 30604-2015. |
