[Synthesis of partial glycerol caprates by using lipase in nonaqueous media]

Enzymatic esterification by reacting caparic acid with glycerol in solvent-free system was studied. Lipases from Pseudomonas fluoresces(PFL), Mucor miehei(MML) and Candida antarictica(CAL) possessed good catalytic activity. The optimal reaction conditions to convert capric acid with CAL are: 60 degrees C, 20-100 u of CAL per gram capric acid, 12% (W/W) of initial water content in glycerol. CAL does not express its 1,3-specificity in final product. Mechanical fraying denatured CAL partly. 96.4% of catalytic activity of CAL recovered after 5 batches of reaction. Extraction with sodium carbonate solution can decrease acid value of product from 9.8 mg KOH/g to 0.68 mg KOH/g. Applying the enzymatic esterification in open system, under vacuum or dehydrating with molecular sieves all dehydrate effectively. Molar ratio of reactants does not influence the total conversion of capric acid but influences the yield of monoglyceride. With certain protocols, the reaction period could be shortened dramatically; conversion of capric acid reached 96.9% in 5 h.