Study On Enzymatic Preparation Of Medium And Long Chain-Fatty Acid Triacylglycerol Rich In α-Linolenic Acid

Medium and long-chain triacylglycerol(MLCT)is a kind of structural ester that contains both medium chain fatty acid(MCFA)and long chain fatty acid(LCFA)and could accelerates lipid metabolism,reduces body fat accumulation,et al.Most studies have focused on the synthesis of MLCT rich in oleic acid(ω-9 fatty acid)and linoleic acid(ω-6 fatty acid),while the researches of MLCT rich in α-linoleic acid(ω-3 fatty acid,ALA)are few.What’s more,the types of commercial lipases used in the synthesis of MLCT are limited.Therefore,using novel lipase to investigate the appropriate enzymatic interesterification technology for the preparation of MLCT rich in ALA,and to explore the relationship between the substance compositions and physicochemical properties of the enzymatic interesterification products is of great significance to give full play to its application value.The main results of this study are as follows:(1)Substance composition and quality analysis of coconut oil and flaxseed oilThe MCFA content of coconut oil(CO)was 58.31%,and flaxseed oil(FO)contained51.98% ALA.The total bioactive component contents in FO and CO were 1190.19 mg/kg and302.62mg/kg,respectively.19 triacylglycerol(TAG)molecules were detected in CO,of which La La La had the highest content,accounting for 20.41%.Most of the TAG molecules detected in FO were mainly with unsaturated fatty acid,and the content of Ln Ln Ln(16.36%)was the highest.Using orthogonal partial least squares discriminant analysis(OPLS-DA)screened that Ln Ln Ln,LLLn,LLn Ln and OOLn were the key TAG molecules of FO,and Ca Ca La,Ca La La,La La La and La La P were the key TAG molecules of CO.(2)Study on the preparation of MLCT rich in ALA by interesterification catalyzed by Lipase UM1The effect factors of enzymatic interesterification to prepare MLCT rich in ALA were investigated systematically,using FO and CO as raw materials.The catalytic efficiency of Lipase UM1 was better than that of Lipozyme TL IM and Novozym 435.The optimum conditions for the interesterification reaction were: 40 °C,the molar ratio of CO to FO was 1:1,the dosage of Lipase UM1 was 25 U/g substrate.The yield of MLCT was 76.59%,and the TAG molecules containing ALA and MCFA(ALA-MLCT)content reached to 45.03%,after 8 h.Scale-up experiments were carried out under optimal conditions,the product contained 75.45%MLCT and 43.57% ALA-MLCT,and the catalytic efficiency of Lipase UM1 was not significantly different from the first batch after 5 batches(p>0.05).(3)Study on the physicochemical properties of the MLCT rich in ALAA comparative study on the physicochemical properties of the oil before and after enzymatic interesterification was carried out.9 species MLCT were detected in the physical blend(PB),accounting for only 18.20% of total TAG composition(excluding ALA-MLCT),and 14 species MLCT(75.45%)were detected in the enzymatic interesterification product(EIE).ALA-MLCT accounted for 43.57% of the total TAG composition in EIE,of which La Ln Ln(9.55%),La PLn(6.73%),La LLn(7.46%),and La SLn(10.99%)were the main ALAMLCT type molecules.Using OPLS-DA modeling analysis,8 spieces TAG molecules were screened as characteristic TAG molecules of EIE.Further analysis found that during the enzymatic interesterification process,the ALA assembled on different TAG molecular backbones,which changed the physicochemical properties of EIE significantly,especially the oxidative stability was improved about 2.44 times(at 100°C).In conclusion,in this study,a interesterification technology for the preparation of MLCT rich in ALA from FO and CO catalyzed by Lipase UM1 was established,and the physicochemical properties such as TAG molecular composition,oxidation stability,thermodynamic properties,solid fat content of the interesterification products were investigated systematically.This study provided a scientific basis for the enzymatic preparation technology and the application of MLCT rich in ALA.