Lipase-catalyzed Acidolysis of Sunflower Oil

CRAPISTE, GUILLERMO; CONSTENLA, DIANA; CARRIN, MARIA ELENA

Madrid, España

Congreso; 4th Euro Fed Lipid Congress; 2006

European Federation for the Science and Technology of Lipids

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 sn-1,3 specific lipases: Lipozyme RM IM (from Rhizomucor miehei, immobilized on ion-exchange resin) and Lipozyme TL IM (from Thermomyces lanuginosa, silica gel-granulated). The effects of the reaction conditions on enzymatic acidolysis were studied. The experiments were performed with a 25 ½ fractional factorial design constituted by sixteen experiments. Randomization and duplicate of assays were used. Substrates and solvents 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 agitation for 4 hours. To stop the reaction, mixture was filtered and washed with hot hexane. Changes in composition of SL were determined through deacidification by alkaline extraction, FAME preparation by cold transesterification with methanolic KOH, and further analysis by capillary gas cromatography. 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 enzyme load (10% wt of substrate) and a high FFA:SO ratio (6:1). There was a negligible difference in palmitic and oleic acids and a little difference in stearic and linoleic acids concentration when Lipozyme RM or Lipozyme TL was used as catalyst.