Enzymatic acidolysis of sunflower oil

CARRIN, MARIA ELENA; CRAPISTE, GUILLERMO

Córdoba, Argentina

Congreso; Congreso Internacional de Ciencia y Tecnología de los Alimentos-2006; 2006

Agencia Córdoba CIENCIA S.E.

Technologies for modification of oils and fats have been investigated in the last years with increasing interest toward lipase-catalyzed reactions. Through enzymatic acidolysis it is possible to incorporate a desired acyl group 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 (FFA) by using two immobilized lipases: Lipozyme RM IM (sn-1,3 specific lipase from Rhizomucor miehei, immobilized on ion-exchange resin) and Novozym 435 (nonspecific lipase from Candida antarctica, immobilized on macroporous polyacrylate resin beads). To study the effects of the reaction conditions on enzymatic acidolysis experiments were performed with a 25 ½ fractional factorial design. Randomization and duplicate of assays were used. Substrates (SO and FFA) and solvent (hexane) were preheated in a water bath to 59±0.5ºC. Adding lipase started the reaction, which was carried out at a laboratory scale (0.5-5 g substrate) in a close system with magnetic agitation for 4 hours. To stop the reaction, mixture was filtered and filter was washed with hot hexane. SL were separated from reaction mixture by deacidification (alkaline extraction with ethanolic KOH). Then, SL were modified to FAME by cold transesterification with methanolic KOH, and further analysis by capillary gas cromatography were done to determine changes in SL composition. The substrate molar ratio (FFA:SO), enzyme type, enzyme load, and presence of water and hexane had a significant effect on the incorporation of palmitic and stearic acids and elimination of oleic and linoleic acids (P£0.05). Replacement of unsaturated by saturated fatty acids in the lipase-catalyzed acidolysis of SO with FFA showed better results when the reaction took place in the presence of water and hexane, at higher values of RM IM enzyme load (10% wt of substrate) and a high FFA:SO ratio (6:1).