Preparation And Function Of The 1,3 - Diacylglycerol Study

Diacylglycerol(DAG)is a sort of healthy edible oil. And it was attracted considerable attention recently because of its multifunctional and nutritional properties. DAG,as a multifunctional additives,is a nature component of fats and oils,which has been used extensively in food industry,pharmaceutical industry,chemical engineering industry and so on.At the end of 2000, DAG has received GRAS (generally recognized as safe) status from the U.S. Food and Drug Administration. However there is no systematic method of industrialization process for DAG in China. A kind of analysis method for glyceride comprising DAG was set up in this thesis. A process for industrial producing DAG was studied systematically, and it is investigated that the method to establish fatty liver model of rats.Enzymatic synthesis of 1,3-DAG was studied by using linoleic acid and glycerol as substrate for Lipozyme RM IM in a solvent free system. The time course of linoleic acid glycoside was compared under different temperature and molar ratio of substrate. The results show that conversion rate of linoleic acid can be increased and the reaction equilibrium shifts to 1,3-DAG synthesis direction with water removal in vacuum. Temperature and molar ratio affect the initial reaction velocity ,conversion rate ,as well as the products composition. A conversion of 90.2% can be obtained when reacting at 60℃for 8 hours ,molar ratio of linoleic acid and glycerol 2∶1 ,and removal of water in vacuum. After purification by molecular distillation ,content of 1,3-DAG in the product can reach 84.25%.The diacylglycerol content analysis was studied by HPLC - RID. In this study ,Nova - Pak 3.9 mm×150 mm silica gel column was adopted , the mobile phase was hexane and isopropanol (50∶1 ,V/ V) . It took 12min for one sample analysis. Quantitative determination was carried out by using external reference method. The results of 1.0～10.0 mg/ml samples fit linear relationship very well . The RSD of the results was 1.43%. The average recovery rate was 101.9%.To investigate the functional effect of 1,3-diacylglycerol. Fifty SD rats were divided into five groups: triacylglycerol(TAG) diet as control group ,100% DAG diet ,70% DAG diet ,30% DAG diet and 30% stanol ester (SE)diet as positive control group. The results show that body weights of 100%DAG, 70%DAG and 30%SE diet are significantly lower than that of TAG control diet from the third week,but there is no significant difference between the 30% DAG diet and TAG diet . The ratio of fat weight to body weight and Lee's index of 100% DAG, 70%DAG,30% DAG and 30% SE diet are significantly lower than that of TAG control diet . The serum TC ,TAG, LDL-C and Apo-B concentration of 100% DAG,70% DAG and 30% SE diet are all significantly lower than that of TAG control diet . The serum HDL-C concentration of these groups are significantly higher than that of TAG control diets.But there are no significant differences between 30% DAG and control diet in these indices. No significant difference in the activity of AST and ALT among the five groups is observed.To investigate the method to establish fatty liver model of rats. The rats were fed on a diet deficient in choline and amino acid and fatty liver models were established successfully. The changes of rat portal vein pressure, ratio of liver weigh/body weigh, and pathological structure of liver were observed. Results:Fourteen days later, much more fatty drop lets were accumulated in the livers of rats, more than two thirds of liver cells had fatty drop lets accumulation after twenty-one and twenty-eight days. The form of fatty liver cells were irregular, liver sinus became narrow and irregular, portal vein pressure of the fatty liver was higher than that of normal one, weights of the liver and body were both lighter than that of normal one. Conclusion:This method is effective and economical to establish fatty liver model of rat in short time.