Study Of Bio-imprinted Candida Rugosa Lipase Catalyzed Synthesis Of L-ascorbyl Palmitate

L-ascorbyl palmitate can be used widely as natural additives in food,medicine and cosmetics with fat-soluble antioxidant and emulsifier characteristics.Relative to the chemical synthesis,the enzymatic synthesis could be performed under milder conditions and the products obtained with higher security,so it can be considered to be a synthetic route with more environmentally friendly.However,economy substrate,the stability of enzyme and production engineering are limiting factors for the development of enzymatic synthesis.In this study,bio-imprinted candidarugosa lipase catalyzed synthesis of L-ascorbyl palmitate was investigated deeply with methyl palmitate as acyl donr.Based on the bio-imprinting of the lipase,we have studied four Immobilization for bioimprinted Candida rugosa lipase,as physical adsorption,sol-gel-encapsulated,Sodium alginate-encapsulated and ion exchange adsorption,After Experimental study,type 214 of ion exchange adsorption was selected to be immobilized carrier,Several factors affecting catalytic activity of bio-imprinted lipase were investigated in details.Bio-imprinted Candida Rugosa lipase with enhanced transesterification activity and operational stability was prepared for using in transesterification of L-ascorbic acid with methyl palmitate in tert-butyl alcohol for the first time.The parameters affected the transesterification activity of the lipase,such as the imprint molecules,the co-solvent,the surfactant coupled with optimal pH and immobilization on ion exchange resin effectively enhanced the transesterification activity and stability of Candida Rugosa lipase.The increase in activity resulting from bio-imprinting and immobilization on ion exchange resin was 4.4-fold.The modified lipase retained 90%of its initial activity after 7 consecutive reaction cycles.The synthesis of L-ascorbyl palmitate through transterification of ascorbic acid and methyl palmitate in tert-butyl alcohol catalyzed by bio-imprinting lipase was studied,Among them solvent studied,The tert-butyl alcohol was found to be the most suitable reaction media and the addition of the molecular sieves was found to be helpful to keep the water activity.The factors affecting the catalytic reaction,such as the substrate concentration,substrate molar ratio,temperature,water activity and the addition of molecular sieve,were investigated.The results showed that,when 0.30g L-ascorbic acid and 0.92g methyl palmitate are catalyzed by 0.45g bio-imprinted lipase in 20mL tert-butyl alcohol with 5g/L molecular sieve added at the 6th hour of the reaction and rotation speed of 200r/min,the conversion of ascorbic acid can reach 63.3%and the concentration of L-ascorbyl palmitate is 22.26g/L after 24h reaction at 50?.