Kinetic behavior of sunflower oil lipase-catalyzed acidolysis

CONSUELO PACHECO; AMALIA CARELLI; MARÍA E. CARRÍN

Seattle, USA

Congreso; 99th AOCS Annual Meeting and Expo; 2008

AOCS

During enzymatic acidolysis a desired acyl group is incorporated onto a specific position of the triacylglycerol to produce structured lipids (SL). In the present study, sunflower oil (SO) was modified with a palmitic-stearic acids blend (SPFA) by using an immobilized sn-1,3 specific lipase: Lipozyme RM IM (from Rhizomucor miehei, immobilized on ion-exchange resin). Changes in SL composition were determined through deacidification by alkaline extraction, FAME preparation by cold transesterification with methanolic KOH, and further analysis by capillary gas chromatography (CGC). Deacidified products were analyzed to quantify by-products as monoglycerides (MG) and diglycerides (DG) by silylation and CGC determination. Nonlinear regression methods were employed to determine kinetic parameters of the enzymatic mechanism representing the reaction from the initial stage until equilibrium. The effects of the reaction conditions (temperature, time, incorporated water) on enzymatic acidolysis were studied. Maximum incorporation of SPFA onto sunflower oil TAG increased with increasing reaction temperature. Kinetic and equilibrium parameters showed temperature dependencies. MG and DG concentrations in water-free systems were stabilized in low levels at short reaction times, while the incorporation of water to the reaction mixture produced a considerable increase in those variables.