ENZYMATIC ACTIVITY OF A COMMERCIAL LIPASE FROM WHEAT GERM UNDER DIFFERENT REACTION CONDITIONS

SALABERRIA, FLORENCIA; PALLA, CAMILA; CARRÍN, MARIA ELENA

Rosario, Argentina

Congreso; World Congress on Oils & Fats; 2015

ASAGA

Lipases are biocatalysts used in a wide variety of industrial processes: food, drugs, biodiesel and detergents. Currently the most used lipases are from microbial and animal origin. However, in recent years, the study of plant lipases has become an interesting alternative for its wide availability and low cost. The commercial lipase from wheat germ (Sigma-Aldrich) is a product whose characterization and application in food has not been developed so far. For this reason it was decided to perform some standard reactions as a general evaluation of the lipase activity (LA) of the enzyme under different reaction conditions.Hydrolysis, acidolysis and esterification reactions were tested in different media varying the enzyme concentration (0.0004-0.061 g/mltot) and reaction time (4, 24, 48 and 72 h). All experiments were conducted at 37 ° C, the optimum temperature for the enzyme according to bibliography. Hydrolysis was evaluated in two different media: M1 used by Sigma-Aldrich (M1: distilled water, Tris buffer pH 7.5, high oleic sunflower oil) and M2 (arabic gum, high oleic sunflower oil, phosphate buffer pH 7) which is a common medium used by several authors in reactions involving plant lipases. The hydrolytic activity was quantified by titration and GLC, where the internal standard method was used to quantify by-products prior derivatization. Esterification was performed with and without hexane using glycerol and butyric acid as substrates (1:10 and 8:1 molar ratio). Acidolysis was carried out in the presence of hexane with sunflower oil and stearic and palmitic acid as substrates (1:6 molar ratio).Hydrolytic activity by titration was 56±10 and 402±159 umol/gWGL?h gsusbtrate) for M1 and M2 respectively. On the other hand, the activity by chromatography was 30463±4435 and 14690±2362 umol/gWGL?h gsubstrate for M1 and M2, respectively, suggesting that the titration method might be subestimating the real activity of the enzyme. Esterification reactions in the presence of hexane reached higher global yields when increasing reaction time and enzyme concentration. Finally, acidolysis showed no activity even when the reaction time was 48 h.