The Studies On Enzymatic Preparation And Purification Of α-linolenic Acid

linseed oil is raw material,compareing the paramaters with the different lipase incatalytic hydrolysis linseed oil,the optimum lipase of catalyzing hydrolysis linseed oil isdetermined,besides,a new technology to purify α-linolenic acid is eatablished.The influencing factors of catalyzing hydrolysis linseed oil by Lipase-AY、LipozymeRMIM、Lipozyme TLIM and Lipozyme435are researched,Included temperature、pH、buttersolution type and surfactant type.The results indicate that the best hydrolyzed result islipase-AY, the hydrolysis ratio reaches94.46%.Determined the influence factors of Lipase-AY catalytic hydrolysis of linseed oil ontemperature、pH、reaction time、enzyme load and the substrate ratio through single factorexperiment, get the optimum conditions;Response surface methodology is applied to optimizethe parameters in hydrolysis of linseed oil by Lipase-AY,The mixed fatty acid product is richin α-linolenic acid,The optimum enzymatic hydrolysis conditions are determined as follows:the reaction temperature is33℃, pH5.8,the substrate ratio is0.9,the enzyme loading is1.2%and the reaction time is3.3h, the validation value is93.92%.The purification effects of thiourea complexation with unit solvent methanol、ethanol、n-propanol、n-butanol and binary solvent methanol-water、ethanol-water、n-propanol-water、n-butanol-water are compared,the results show that the effect of unit solvent to thioureacomplexation purification α-linolenic acid is bad, the average relative content of α-linolenicacid under60.00%;Binary solvent methanol-water is best, the average relative content ofα-linolenic acid is70.99%;Polar additives acetic acid can improve the average relative contentof α-linolenic acid of73.65%.The single factor experiment determined factors affecting the thiourea complexpurification of reaction temperature, thiourea and fatty acids ratio, solvent and fatty acids ratioand polar additive dosage are studied,get the best condition of purification of alpha linolenicacid;Response surface methodology is applied to optimize the parameters in purifyingα-linolenic acid by thiourea complexation.The optimal purification process conditions asfollows:thiourea and fatty acid ratio is5.5, alcohol-water and fatty acid ratio is29.0,aceticacid and fatty acid ratio is0.5,the reaction temperature is63℃,the reaction time is204min,the average relative content of α-linolenic acid is70.61%,the extraction yield is49.26%, the yield is36.80%.After six washing, thiourea residue in the α-linolenic acid productdecreased to1.58mg/L.Oven method is used to evaluate the oxidation stability of α-linolenic acid, the resultsshow that peroxide value and the total oxidation value can better judge theα-linolenic acidoxidation stability,7h is the cut-off point of α-linolenic acid from oxidation induction periodto oxidation accelerated period.