Synthesis Of Diglycerides Using Immobilized Lipase From Candida Sp.99-125

Diglycerides have been used widely in many fields including food additive, pharmacy and chemical engineering. Recently a kind of oil rich in1,3-DAG has been a popular healthy edible oil due to its specific metabolism process in body, however, Application of DAG is limited by its high cost of production, so an efficient and economic process to synthesize DAG has to be made.In the prensent work, enzymatic synthesis of diolein was studied by using oleic acid and glycerol as substrate for Immobilized lipase from Candida sp.99-125in a solvent-free system. Through researh on different reaction system, four kinds of lipases, compare of several kinds of desiccants on convertion rate of fatty acid, a basic reaction system was builded, which is solvent-free, Candida sp.99-125as enzyme,5A molecular sieve as desiccant. An equation that contains three variants(temperature, molar ratio, lipase dosage) is set up by using RSM(response surface method):Y=-60.408+1.592833X1+214.7667X3-0.023792X12-187.963X32-7.058667X22A set of optimized reaction conditions includes that temperature is32℃, molar ratio of FFA to glycerol is1.6:1, lipase dosage is0.5g/(5.65g FFA), in above condition a conversion rate of DAG reaches41%.Conversion rate of FFA and DAG can reach more than90%and60%when spontaneous evaporation and vacuum were used for removing water produced during esterification. Through reseach on lipase dosage, molar ratio, temperature of reaction, a central point for experiment design of RSM was found,which is0.6g/(5.65g FFA), molar ratio2:1,50℃, spontaneous evaporation for removing water. Two equations about convension rate of FFA and DAG were build which have great prediction for experimental results.Y1=-267.437+12.03787X1+45.508757X3-0.119112X12-0.011604X1X2-12.36625X32-0.001705X22Y2=-362.089+12.20225X,+2.191823X2-0.113425X12-0.022135X1X2-13.4475X32-0.005841X22Synthesis reaction of diglycerides by glycerolysis of soybean salad oil with glycerol in a solvent-free system catalyzed by immobilized lipase from Candida sp.99-125was discussed. The effect of temperature and substrate molar ratio on the glycerolysis was studied.