Application Of A Cold-active Lipase In Transesterification Of Functional Oils

The optimal temperature of cold-active lipase is low,and it can play a role at room temperature,which greatly saves energy production.There is great potential for the cold-active lipase in industrial applications.In this study,the laboratory homemade cold-actived lipase Lip8102 was applicated.Its hydrolytic properties and transesterification properties were determined by the p-nitrophenol method and the reaction of triolein and n-caprylic acid,respectively.It was applied to catalyze transesterification between triglyceride-type fish oil with a content of 29.39%of omega-3 fatty acids and 77.92%of ethyl-type fish oil.The composition of fatty acids and the kinetics of thermal oxidation were analyzed under the optimal reaction conditions.It was also applied to the preparation of medium/long chain fatty acids triglycerides from transesterification of soybean oil and ethyl ester of medium chain fatty acid represented by ethyl caprylate to investigate the catalytic effects of this cold-actived lipase on lipids of different carbon chain lengths.The results of enzymatic properties showed that the optimal hydrolysis and transesterification temperature of lipase Lip8102 were all 30℃.It was stabilized between 10℃ and 40℃.The optimal pH of hydrolysis was 7.5,and it was stabilized at pH 6.0～9.0.The optimal hydrolysis substrate was p-Nitrophenylphthalate(pNPC 10).Low concentrations of methanol,EDTA,Ag+ and Ca2+ promoted its enzyme activity.Methanol with a concentration of 10%and 20%,Tween 60 and Span 80 with a concentration of 1%promoted its transesterification activity.The response surface optimization of the cold-active lipase Lip8102 catalyzed transesterification of fish oil was carried out.The optimal reaction conditions were as follows:enzyme addition was 38U,reaction temperature was 29℃,substrate mass ratio of triglyceride-type and ethyl-type was 6:5,reaction time was 18.6h.In the optimal conditions,the content of EPA and DHA in the product of triglyceride-type fish oil were 28.09%and 17.60%,respectively,and the total content was 45.69%,which was similar to porcine pancreatic lipase and Novozyme 435,about 6%lower than Lipozyme TL IM.Therefore,there were great potential for the cold-active lipase Lip8102 application in the transesterification of preparation of high content omega-3 fatty acid triglyceride-type fish oil.The thermal oxidation kinetics of the optimal product triglyceride fish oil was studied by differential scanning calorimetry(DSC).The results showed that the activation energy of triglyceride-type fish oil products with ω-3 fatty acid content of 45.69%was about 34KJ·mol-1 higher than that of commercial ethyl-type with omega-3 fatty acid content of 50.12%.And the rate constant and half-life of ther mal oxidation reaction of the two kinds of fish oil were similar.The kinetics of the thermal oxidation process analyzed by Flynn-Wall-Ozawa method and Kissiger method.The parameters were consistent.This provided basic data and theoretical guidance for the processing,storage,and consumption of product triglyceride-type fish oil.The cold-active lipase Lip8102 catalyzed the transesterification of soybean oil and ethyl caprylate to the prepare medium/long chain fatty acids triglycerides.The preliminary results showed that the content of caprylic acid in the product triglyceride was 31.86%.There were potential for the cold-active lipase Lip8102 application in the preparetion of medium/long chain fatty acids triglycerides by transesterification reaction.