Abstract

Synthesis of ascorbyl palmitate by enzymatic esterification of palmitic acid and ascorbic acid was conducted in an organic medium with Pseudomonas stutzeri lipase TL immobilized in different supports and its performance was compared with commercial Novozym 435 lipase used as a reference. The enzyme was immobilized in different supports and the best catalyst was selected in terms of immobilization yield and mass specific activity to perform the reactions of synthesis. Synthesis of ascorbyl palmitate was optimized considering temperature, substrate molar ratio and enzyme to limiting substrate mass ratio as variables, and substrate conversion and specific productivity as evaluation parameters. The best reaction conditions for immobilized lipase TL were 55 A degrees C, 1:5 ascorbic to palmitic acid molar ratio, and 1:10 lipase to ascorbic acid mass ratio, obtaining 57 % substrate conversion and a specific productivity of 0.013 [g ascorbic acid/(g enzyme x min)]; the best conditions for Novozym 435 were 70 A degrees C, ascorbic to palmitic acid molar ratio 1:10, and 1:10 lipase to ascorbic acid mass ratio, obtaining 51 % substrate conversion and a specific productivity of 0.016 [g ascorbic acid/(g enzyme x min)].