Enzymatic synthesis of structured lipids: Transesterification of triolein and caprylic acid ethyl ester

Structured lipids were successfully synthesized by lipase-catalyzed transesterification (ester interchange) of caprylic acid ethyl ester and triolein. The transesterification reaction was carried out in organic solvent as reaction media. Eight commercially-available lipases (10% w/w substrates) were screened for their ability to synthesize structured lipid by incubating with 100 mg triolein and 78.0 mg caprylic acid ethyl ester in 3 mL hexane at 45 degrees C for 24 h. The products were analyzed by reverse-phase high-performance liquid chromatography with evaporative light-scattering detector. Immobilized lipase IM60 from Rhizomucor miehei converted most triolein into structured lipids (41.7% dicapryloolein, 46.0% monobcapryloolein, and 12.3% unreacted triolein). However, lipase SP435 from Candida antarctica had a higher activity at higher temperature. The reaction catalyzed by lipase SP435 yielded 62.0% dicapryloolein, 33.5% monocapryloolein, and 4.5% unreacted triolein at 55 degrees C. Time course,-incubation media, added water, and substrate concentration were also investigated in this study. The results suggest that lipase-catalyzed transesterification of long-chain triglycerides and medium-chain fatty acid ethyl ester is feasible to synthesize structured lipids.