Optimized enzymatic synthesis of ascorbyl esters from lard using Novozym 435 in co-solvent mixtures

A mild and efficient method for the conversion of fatty acid methyl esters from lard into ascorbyl esters via lipase-catalyzed transesterification in co-solvent mixture is described. A solvent engineering strategy was firstly applied to improve fatty acid ascorbyl esters production. The co-solvent mixture of 30% t-pentanol:70% isooctane (v/v) was optimal. Response surface methodology (RSM) and central composite design (CCD) were employed to estimate the effects of reaction parameters, such as reaction time (12–36 h), temperature (45–65 °C), enzyme amount (10–20%, w/w, of fat acid methyl esters), and substrate molar ratio of fatty acid methyl esters to ascorbic acid (8:1–12:1) for the synthesis of fatty acid ascorbyl esters in co-solvent mixture. Based on the RSM analysis, the optimal reaction conditions were determined as follows: reaction time 34.32 h, temperature 54.6 °C, enzyme amount 12.5%, substrate molar ratio 10.22:1 and the maximum conversion of fatty acid ascorbyl esters was 69.18%. The method proved to be applicable for the synthesis of ascorbyl esters using Novozym 435 in solvent.