Synthesis Of Functional1,3-Diacylglycerol And Estimation Of Stability

This study is divided into two steps to research1,3-diglycerides. In the first step, the effect of fatty acid sucrose esters as emulsifier on lipase-catalyzed glycerolysis of blending oil in solvent-free system was investigated. In the preliminary study, it took too long time (43h) to get only41.97%1,3-DAG in the solvent-free and surfactant-free system, but a long time would reduce the repetition rate of lipase using. This is a drawback for practical purposes. In order to get high content of1,3-DAG in a short time, fatty acid sucrose esters was added in the reaction system. The best reaction condition was determined and then the synthetic product was analysed by HPLC. In the second step, the physicochemical property and the oxidative stability of diglyceride were studied with the blend oil as contrast.In the reaction system which added fatty acid sucrose esters, the best reaction condition was reaction temperature:60℃, blend oil/glycerol(mol/mol):1:1, the content of Lipase Novozym435:8%, the content of SE:0.5%, HLB value:SE-1170, reaction time:24h. The content of1,3-DAG could come up to42.61%in this circumstances.The physicochemical property of diglyceride and its oxidation in different temperature were studied with triglyceride as contrast. The results showed that, in the two oxidizing condition, the content of unsatruated fatty acid was lower and lower and the saturated fatty acid increase gradually with the extension of time. The acid value and peroxide value of untreated rich-diacylglycerol oil rised slightly after60℃continuous heating process. All the acid value, peroxide value and carbonyl value of untreated rich-diacylglycerol oil were higher than the untreated blend oil under180℃continuous heating. Afer3h heating, the peroxide value of rich-diacylglycerol oil and blend oil reached to14.08meq/kg and6.97meq/kg separately, and the carbonyl value reached to37.83meq/kg and37.75meq/kg separately. Carbonyl value is also proportional to the heating time, and3hours of heating was significantly higher than1hour heating.This study described the feasibility of enzymatic synthesis of1,3-diglycerides in short reaction time by adding fatty acid sucrose esters. The composite diglyceride had the similar physicochemical property. But it got a lower thermal oxidative stability than blend oil.