Study On The Enzymatic Preparation Of 1,3-diglycerol And It's Efficacy Evaluation

Diacylglycerol(DAG)is a natural trace component in vegetable oils and fats,and is recognized as a safe food component,but its content is usually less than 5%.DAG can be divided into two isomers,1,2-DAG and 1,3-DAG,and the ratio of the two is generally 3:7.A large number of studies have shown that 1,3-DAG has the functions of inhibiting fat accumulation,slowing down weight gain,improving postprandial blood lipid levels,preventing fatty liver and preventing hyperlipidemia and its related cardiovascular and cerebrovascular diseases.In recent years,the number of obese people in my country has been increasing.1,3-DAG,as a functional healthy oil that can reduce fat accumulation and slow down weight gain,has received extensive attention from the society.However,the current industrial production of 1,3-DAG is mostly chemical method,which has high cost and low yield of 1,3-DAG,and also causes environmental pollution.If the enzymatic hydrolysis method is used,the yield of 1,3-DAG can be significantly improved by using lipase to directly catalyze the hydrolysis of TAG.However,no lipase with the ability to specifically hydrolyze the acyl group at the Sn-2 position of TAG has yet been found.In this paper,Candida antarctica lipase A,which has the ability to hydrolyze TAG Sn-2 bonds,was selected,and the one-step enzymatic hydrolysis method was used to prepare 1,3-DAG,which significantly shortened the production process and improved production efficiency.The free fatty acids and monoglycerides in the product were removed by distillation,and a preliminary study on the efficacy of 1,3-DAG was carried out.The main findings are as follows:(1)In this project,high oleic sunflower oil was selected as the raw material,and1,3-DAG was obtained by catalyzing the hydrolysis of TAG by Candida antarctica lipase A.The effects of enzymatic hydrolysis time,enzymatic hydrolysis temperature,enzyme addition amount and water addition amount were investigated.Influence of 1,3-DAG content in enzymatic hydrolysis products,the enzymatic hydrolysis process conditions were optimized by single factor experiment and response surface methodology,and 1,3-DAG content was determined by high performance liquid chromatography evaporative light scattering detector.Finally,the optimal process conditions for lipase-catalyzed hydrolysis of TAG were screened out as follows: the enzyme addition amount is 3850 u/g(accounting for oil weight),the water addition amount is 32.0%(accounting for oil weight),the enzymatic hydrolysis temperature is70.5 °C,and the reaction is 9.1 h.The content of 1,3-DAG prepared under the conditions was34.36%.(2)The 1,3-DAG in the enzymatic hydrolysis product was separated and purified by molecular distillation,and a large amount of free fatty acids and monoglycerides produced in the enzymatic hydrolysis reaction were removed.The effects of distillation temperature,scraper rotation speed and feed rate on the separation and purification of 1,3-DAG were studied by single factor experiments.According to the results of single factor experiments,orthogonal experiments were designed to optimize the molecular distillation process again.The experimental results found that the distillation temperature had the greatest influence on the separation and purification of 1,3-DAG,followed by the scraper speed,and the feed rate had the least influence,but all three factors had significant effects on the separation and purification results.The optimal conditions of the molecular distillation process were finally determined as distillation temperature of 150?,scraper speed of 300 r/min and feed rate of 3m L/min.The obtained 1,3-DAG content could reach 41.24%.(3)Eighteen obese mice(ob/ob mice)were randomly divided into three groups: 40%1,3-DAG group,80% 1,3-DAG group and normal control group(TAG group with the same fatty acid profile as 1,3-DAG),through 31 weeks of dietary intervention to study the effect of long-term intake of 1,3-DAG on ob/ob mice,the experimental results show that 1,3-DAG can reduce fat accumulation,reduce body weight gain,and reduce blood lipids etc.have a positive effect.The food intake and body weight of the three groups of mice were analyzed,and it was found that the food intake of the mice in the 1,3-DAG group was higher than that of the blended oil group,but their body weight was lower than that of the blended oil group,indicating that 1,3-DAG was not easily converted into fat and accumulated in the body,can slow down weight gain.Blood indicators in mice showed that long-term 1,3-DAG dietary intervention improved blood lipid levels.The pathological sections of the adipose tissue of the three groups of mice were observed,and it was found that the adipose tissue cells in the1,3-DAG group were more numerous,densely arranged,and the lipid droplet size was small,which was closer to the adipose tissue of normal mice.In addition,studies on the gut microbes in mice were performed and found that dietary intervention had little effect on the overall diversity of gut microbes,but the level of Firmicutes was reduced in the 1,3-DAG group.