Preparation Of Functional Microalgae Phospholipids Catalyzed By Lipase

Lysophospholipids are very important in solving problems of membrane-chemistry and biochemistry.In recent years,studies have shown that lysophospholipids play important roles in physiological and pathological processes.Such as inflammation,reproduction,angiogenesis,tumors,atherosclerosis and nervous system regulation.Intake of n-3 PUFAs could prevent and treat chronic inflammation,obesity,diabetes,and even cancer.Moreover,many studies have domonstrated that n-3 PUFAs-enriched LPLs can prevent vascular dysfunction,monocyte adhesion and so on.Currently,the methods of preparing lysophospholipids include chemical methods and enzymatic mathods.In contrast to chemicial methods,the enzymatic approach offers considerable advantages such as mild conditions and high selectivity or specificity,leading to the generation of products that cannot easily be obtained by chemical methods.Therefore,enzymatic-catalyzed preparation of lysophospholipids is one of the hot trends in the study of oil modification.The enzymatic preparation of lysophospholipids including hydrolysis reaction and/or alcoholysis reaction.At present,the main source of phospholipid products circulating in the market is soybeans and egg yolks.Compared with soybeans and egg yolks,marine microalgae like Nannochloropsis oculata have many advantages of fast growth rate,high oil content and high rich of EPA.Therefore,this thesis uses lipase as biocatalyst and microalgae phospholipids as substrates,optimizing its process parameters and providing a theoretical basis for the industrial production of lysophospholipids.The main studies and results are as follows:1.Four commercial lipases(Novozym 435,Lipozyme TL IM,Lipozyme RM IM and CAL-A)were used as catalysts to screen the enzymes.Then discussing the influence factors about the preparation of lysophospholipids and determineding the optimal conditions of reaction.The raw material comes from microalgae phospholipids.The results showed that the Lipozyme TL IM was the best catalysts.And the optimum conditions were as follows: the volume of phosphate buffer to quality of phospholipids is 2:0.1(v/w),lipase dosage 8%(based on the amount of phospholipids),reaction temperature 45?,reaction time 14 h,phosphate buffer pH 7.Under the conditions,the degree of hydrolysis reached amaximum of 42.4%.2.The alcoholysis of microalgae phospholipids by lipase Lipozyme TL IM in ethanol was studied.What's more,the difference between phospholipid hydrolysis and alcoholysis was discussed and the optimum conditions of reaction were investigated.The results showed that the optimum conditions were as follows: the weight ratio of ethanol to oil was 3:1,water content was 10%(based on the total amount of substrate),lipase loading was 22%(based on the amount of phospholipids),reaction temperature was 35?,reactime time was 8h.Under this reaction,the efficiency of alcoholysis was higer than the hydrolysis and the degree of ethanolysis was 75.1%.3.Using lipase catalyzed alcoholysis to prepare for lysophospholipids and recovery the n-3 PUFAs.First of all,the Novozym 435 was screened out from three lipase to have the best catalytic effect.On this basis,the effects of immobilized lipase and liquid lipase on the catalytic alcoholysis efficiency were investigated.Taking immobilized lipase Novozym 435 and liquid lipase CAL-B as biocatalyst and investigating the optimal conditions.The reaction parameters of Novozym 435 were optimized as follows: the weight ratio of ethanol to oil was 9:1,water content was 2%(based on the total amount of substrate),lipase loading was 15%(based on the amount of phospholipids),reaction temperature was 40?,reactime time was 12 h.Under this reaction,the ethanolysis percentage and n-3PUFAs recovery was 98.3% and 88.3% respectively.The results of CAL-B were listed as follows: the ratio of ethanol to oil was 1:0.1(the volume of ethanol to quality of phospholipids is 1:0.1,v/w),water content was 0%(based on the total amount of substrate),lipase loading was 1.2%(based on the amount of phospholipids),reaction temperature was 50?,reactime time was 12 h.Under this reaction,the ethanolysis percentage and n-3PUFAs recovery was 74.2% and 92.8% respectively.4.Microalgae phospholipids and caprylic acid were selected to synthesize structured phospholipids by enzymatic acidolysis using 4 kinds of commercial lipase(Novozym 435?Lipozyme TL IM?Lipozyme RM IM and CAL-A).First of all,selecting the Lipozyme TL IM as the best biocatalyst.The results were concluded as follows:lipase loading was 10%,the mole ratio of caprylic acid to phospholipids was 6:1,reaction temperature was 50?,water content was 10%,reaction time was 24 h.Under these conditions,the incorporation rate was about 31.6%.