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 ei cosapentaenoic acid (EPA) are potentially health-beneficial water-in-o il emulsifiers useful in the food industry. These esters were synthesi zed enzymatically to overcome the problems associated with chemical pr ocesses. The-products were analyzed by gas chromatography; The immobil ized Mucor miehei lipase was found to be the best enzyme for the synth esis of both propylene glycol monoesters of EPA and DHA among nine lip ases tested. The anhydrous enzyme and hydrophobic organic solvents wer e favored for the of both monoesters. The yields of monoesters were al so affected by temperature, pH memory, fatty acid/propylene glycol rat io, and reaction time. The yields of PGMDHA and PGMEPA with 50 mM fatt y acid and 225 mM propylene glycol as substrates in 1 mL solvent mixtu re (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 b oth PGMDHA and PGMEPA.