| L-ascorbyl octanoate was synthesized through lipase-catalyzed esterification in organic system with mid-chain fatty acid n-octanoic acid as acyl donor. The reaction parameters that highly influenced the conversion rate of L-ascorbic acid were selected as main variables to design the response surface experiment on the basis of preliminary experiments, then a regression model was established and the optimal synthesis conditions were obtained. The results indicated that reaction time, reaction temperature, interaction between reaction time and reaction temperature and interaction between reaction time and substrate concentration had significant effects on the conversion rate of L-ascorbic acid (p＜0.05), and the regression model could be used to predict the conversion rate of L-ascorbic acid. The optimal enzymatic synthesis conditions of L-ascorbyl octanoate were obtained as follows: reaction time 11.45 h, substrate(L-ascorbic acid) concentration 0.24 mol/L, reaction temperature 55.3℃, dosage of lipase (based on the mass of L-ascorbic acid) 19.18%. Under these conditions,the conversion rate of L-ascorbic acid reached 83.31%. In addition, the product was characterized by IR, MS, 1H NMR and 13C NMR,and the result showed that n-octanoic acid was introduced into the sixth hydroxyl of L-ascorbic acid. |
