SYNTHESIS OF PROPYLENE-GLYCOL MONOESTERS OF DOCOSAHEXAENOIC ACID AND EICOSAPENTAENOIC ACID BY LIPASE-CATALYZED ESTERIFICATION IN ORGANIC-SOLVENTS

Propylene glycol monoesters (PCM) of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are potentially health-beneficial water-in-oil emulsifiers useful in the food industry. These esters were synthesized enzymatically to overcome the problems associated with chemical processes. The-products were analyzed by gas chromatography; The immobilized Mucor miehei lipase was found to be the best enzyme for the synthesis of both propylene glycol monoesters of EPA and DHA among nine lipases tested. The anhydrous enzyme and hydrophobic organic solvents were favored for the of both monoesters. The yields of monoesters were also affected by temperature, pH memory, fatty acid/propylene glycol ratio, and reaction time. The yields of PGMDHA and PGMEPA with 50 mM fatty acid and 225 mM propylene glycol as substrates in 1 mL solvent mixture (hexane/t-butyl alcohol = 9.1), catalyzed by Lipozyme IM-20 (50 mg) at 40 degrees C for 24 h, were 47 and 49 mM, respectively. The enzyme still retained over 60% of its original activity after 10 d of batch-type operation (1 d per cycle) at 40 degrees C: for the synthesis of both PGMDHA and PGMEPA.