Study On Lipase-Catalyzed Synthesis Of Structured Lipids

Lipid is one of the three major nutrients, it could humanity supply the essential fatty acids that could not be synthesized by ourselves, and it also an important factor in food flavor formation, which plays a special and important role in the human diet composition. However, with the improvement of people’s living standards, as the lipids’high energy characteristics, excessive intake could cause some health problems. Therefore, the research of new modification lipids that maintain physiological functions, while also reducing the negative effects has a special necessity. Structured lipids are the main focus in the new lipids research.Dairy has a long history and it is an indispensable part of people’s diet culture. As the primary energy supply components and flavor, cream quality is pivotal to dairy. In this paper, the synthesis of structured lipids was obtained by transesterification of cream and free fatty acids with the catalysis of immobilized lipase Lipozyme TLIM.Firstly, a method of using ultra performance liquid chromatography (UPLC) to detect the fatty acids composition and positional distribution was established. With the characteristics that 2-bromoacetophenone derivatization reaction occurs only with free fatty acids, using UPLC with the moving phase of methanol-water-acetonitrile to detect the fatty acids composition and positional distribution of cream. Compared with conventional GC method, this method has the advantages in convenience, precision.Secondly, using the incorporation of caprylic acid as index, through the single factors and response surface analysis experiments to establish the optimal reaction conditions. The result is that in the hexane solvent, the molar ratio of cream and caprylic acid was 1:4, the dosage of lipase was 14.64%, the reaction time was 17.7h and the reaction temperature was 55℃. Under these optimal reaction conditions, the incorporation of caprylic acid could reach 45.12%. The forecasting model is accurate and reliable by confirmatory tests.Thirdly, in order to examine the physicochemical properties of structured lipids, a 10-fold expansion experiment was established. The experiment results showed that the yield of glycerides was 74.65%, and the iodine value lowered 13.72% while the saponification value increased 19.36%. The results indicating that the caprylic acid successfully replaced the long-chain polyunsaturated fatty acids in original cream.Finally, in order to study the immobilized lipase Lipozyme TL IM catalytic ability of different substrates, using capric acid and linoleic acid to produce structured lipids with cream. The results showed that compared to the caprylic acid structured lipids, the lipase catalytic activity of catalyze capric acid structured lipids showed no significant differences, but it was relatively weak in the linoleic acid structured lipids.