Synthesis of the 'green apple ester' ethyl valerate in organic solvents by Candida rugosa lipase immobilized in MBGs in organic solvents: Effects of immobilization and reaction parameters

Ethyl valerate. also known as the green apple flavor is well known for its wide applications in the areas of food, pharmaceuticals and cosmetics industries. Candida rugosa lipase was immobilized in microemulsion based organogels(MBGs)and used for ethyl valerate synthesis in organic solvents. Various immobilization and reaction parameters were scrutinized for enhancement of ester production. Among the immobilization parameters, sodium bis-2-(ethylhexyl) sulfosuccinate (AOT), n-heptane and gelatin were found to be the highest yielding combination. Cyclohexane was found to be the solvent of choice as the react ion medium while pH 7, 40 degrees C and 1:1.6 ratio of valeric acid to ethanol were the reaction parameters exhibiting highest ester formation. The organogels were highly stable in the solvents and were reused for nine cycles with meager loss of activity. Also, immobilized enzyme was thermostable at 50-70 degrees C for ten hours. Hence, MBGs verify to be a promising enzyme immobilization system for ester synthesis in organic solvents. (C) 2009 Elsevier B.V. All rights reserved.