Study On Preparation Of Enriched Dilinoleoylphosphatidylcholine By Lipase

Phosphatidylcholine (PC) is a basic constituent of cell membranes, and plays a vital role in maintaining physiological activity of membranes and metabolic process. As the primary constituent, dilinoleoylphosphatidylcholine (DLPC) possesses important significance in the biochemistry and cellular physiology. Medical studies indicate that DLPC is effective in promoting hepatocyte regeneration, alleviating steatosis and cell necrosis, improving lipids metabolism of blood and liver, and treatment and prevention of cirrhosis and fibrosis.For increasing the content of DLPC in soy PC, immobilized lipase Lipozyme TL IM-catalyzed acidolysis of soy PC and linoleic acid (LA) was studied in heptane in this thesis. Firstly, commercially available immobilized lipases and reaction medium were examined and Lipozyme TL IM was finally selected for catalyzing acidolysis in heptane. Secondly, the six major factors chosen were PC concentration (PC/heptane, g/mL), substrate ratio (LA/PC, g/g), lipase dosage (based on substrates, wt.%), water addition (based on solvent,μL/mL), reaction time (h) and reaction temperature (℃) through determining the content of LA, followed by screening by Plackett-Burman Design. The final three significance factors (substrate ratio, lipase dosage and reaction temperature) were confirmed. Based on this result, the best level and interaction of these three factors were discussed by Response Surface Methodology for further optimization. The best fitting quadratic model was determined by regression and backward elimination and the significance were tested by ANOVA. Finally, the optimal reaction conditions for the production of structured PC by Lipozyme TL IM-catalyzed acidolysis were found to be PC concentration, 0.25g/mL; substrate ratio, 2.81; lipase dosage, 23.92%; water addition, 3μL/mL; reaction time, 61.57℃; reaction temperature, 48h. At optimum conditions, the content of the product was 83.24%, and immobilized lipase Lipozyme TL IM revealed good stability. All of physical and chemical indexes of the product were in accordance with SB/T 10206-1994. After isolation, identification and determination of HPLC/TLC/HPLC- MS, the content of DLPC of PC was 69.07% in the condition of UV-205nm.