PRODUCTION OF SPECIFIC-STRUCTURED TRIACYLGLYCEROLS BY LIPASE-CATALYZED INTERESTERIFICATION IN A LABORATORY-SCALE CONTINUOUS REACTOR

A laboratory-scale continuous reactor was constructed for production o f specific structured triacylglycerols containing essential fatty acid s and medium-chain fatty acids (MCFA) in the sn-2 and sn-1,3 positions , respectively. Different parameters in the lipase-catalyzed intereste rification were elucidated. The reaction time was the most critical fa ctor. Longer reaction time resulted in higher yield, but was accompani ed by increased acyl migration. The concentration of the desired triac ylglycerol (TAC) in the interesterification product increased signific antly with reaction time, even though there was only a slight increase in the incorporation of MCFA. Increased reactor temperature and conte nt of MCFA in the initial reaction substrate improved the incorporatio n of MCFA and the yield of the desired TAC in the products. Little inc rease of acyl migration was observed. Increasing the water content fro m 0.03 to 0.11% (w/w substrate) in the reaction substrate had almost n o effect on either the incorporation or the migration of MCFA, or on t he resulting composition of TAG products and their free fatty acid con tent. Therefore, we conclude that the water in the original reaction s ubstrate is sufficient to maintain the enzyme activity in this continu ous reactor. Since the substrates were contacted with a large amount o f lipase, the reaction time was shorter compared with a batch reactor, resulting in reduced acyl migration. Consequently, the purity of the specific structured TAG produced was improved. Interesterification of various vegetable oils and caprylic acid also demonstrated that the in corporation was affected by the reaction media. Reaction conditions fo r lipase-catalyzed synthesis of specific structured TAG should be opti mized according to the oil in use.