Study On Preparation Technology Of Immobilized Lipase

Immobilized enzymes are prepared by immobilizing enzymes on carriers through adsorption,cross-linking,etc.Immobilized enzymes technology not only does not change the original catalytic properties of enzymes,but also can be easily recycled and reused.In this paper,the preparation of immobilized lipase was optimized and its catalysis for transesterification of oil was studied.The main research contents and results are as follows:Lipase activity is easily lost in the immobilization process,so the active center of lipase is protected by pre-added olive oil and then cross-linked.In the isooctane environment,the hydrolytic activity of immobilized lipase prepared by adding oil pretreatment was 1.9 times higher than that without pretreatment.The immobilized lipase was prepared by using chitosan-macroporous resin as carrier,and the best preparation conditions were obtained by single factor and orthogonal experimental analysis.The optimum conditions are olive oil addition 5 mL,pretreatment time 20 min,pretreatment temperature 30 °C,chitosan concentration 1.5%,sorbitol concentration 2%,glutaraldehyde concentration 0.7%,activation time 1 h,fixed time 10 h,the enzyme-carrier ratio of 1: 10,fixed temperature of 25 °C,the obtained lipase hydrolase activity was 536 U/g,the enzyme activity recovery rate of 73%.Despite the loss of enzyme activity after immobilization,the immobilized enzyme still retained 59.93% of the enzyme activity after 10 times of use because of its advantages of easy recovery,reusability and high stability.The optimum reaction pH of free enzyme and immobilized enzyme was 7 by experiment.In the acidic environment,the stability of the immobilized enzyme was higher than that of the free enzyme.The reaction conditions were optimized by single factor and orthogonal experiments in the reaction of immobilized lipase-catalyzed oil esterification.The experimental results show that the optimal conditions are 10 g oleic acid,20% water addition,5 mL n-hexane addition,1 g immobilized enzyme,alcohol-oil molar ratio 4: 1,45 °C for 16 h.The esterification rate of immobilized lipase to oleic acid was 92.15%,Under the optimum reaction conditions,the esterification rate of immobilized lipase remained above 50% after 9 times of use,which indicated that the immobilized lipase had good reusability and had important significance in industrial production.