Synthesis Of L- Ascorbyl Palmitate Catalyzed By Lipase In Anhydrate Medium

L-ascorbyl palmitate (L-AP) is a kind of antioxidant with more reliability, and is broadly used in many fields beyond as the food additive, for example used in the industry of cosmetic and papermaking. In this paper we studied the synthesis reaction catalyzed by lipase, in which the proper lipase and organic solvent are determined, and also the optimized process conditions, such as temperature, enzyme, reactants and water concentrations. We found that Novozyme435 lipase and tert-butyl are the prefer couple, in which the enzyme shows more reactive. In addition, tert-butyl alcohol and tert-amyl alcohol are confirmed to be the water-mimicking solvents of the lipase-Novozyme435, and we found that the enzyme-catalyzed reaction conforms to the M-M equation. We got the dynamic parameters Km and Vm according to the dynamic experiments and Langmuir method, which help us to check that palmitic acid is a preferable substrate than methyl palmitate in the reaction. The catalyzed reaction is faster in the water-mimicking solvent than in conventional non-aqueous medium, because no phases interfaces exist in the former. The purpose product is easily to separation and purification, also the recovering process of materials is easily to be made, because there are no side reactions occurred in the mild condition.The quality items of L-AP prepared meet the national food additive standard, and the antioxidative performances of L-AP prepared and other antioxidants are tested and compared, L-AP and tocopherol couple shows prefer antioxidation than commonly used antioxidants, such as BHA, BHT and TBHQ in some applications.