Purificação de lipases fúngicas visando aplicação em tratamento de óleo residual de fritura

Abstract

This study aimed at evaluating the purification of the enzyme lipase from Aspergillus niger by solid state fermentation (SSF) using canola cake a substrate. The purification of the enzyme with ionic medium strength and organic solvent precipitation techniques was evaluated using subsequent application of lipase as catalyst in frying residual oil hydrolysis reaction. The performance of the lipase enzyme precipitation by changing ionic strength by adding salt and precipitation with organic solvents was studied using experimental design techique. The effects of salt NaCl concentration (0 – 1.0 mol/L), solvent concentration (Acetone and ethanol) (10 - 90%) and the rate of addition to the crude extract (mL/min) .The specific activity of the enzyme, the purification factor and the yield of the enzymatic activity were evaluated as response. The change in ionic strength of the medium by the addition of salt (0.5 mol/L NaCl) and precipitation with organic solvent ethanol (50%) increased the specific activity from 2.90 U/mg to 28.50 U/mg, resulting in a purification factor of 9.82 fold and a yield of 157.31%. The ionic strength change of the crude extract by the addition of salt (0.5 mol/L NaCl) followed by precipitation with organic solvent acetone (50%) obtained an increase in specific activity of 2.90 U/mg for 33.63 U/mg, resulting in a purification factor of 11.60 fold and a yield of 263.77%. After purification of the enzyme, it has been used in the hydrolysis of frying residual oil. Hydrolysis was performed using an oil: water ratio of 1: 3 (v:v) and enzymatic concentration of 15% (v/v), where the release of 753.07 μmol/mL of free fatty acids ) for the enzyme precipitated with ethanol and 421.60 μmol/mL free fatty acids (FFA) for the enzyme precipitated with acetone were obtained. This method of lipases precipitation enzyme has been shown to be a promising and low cost technique for the purification of this enzyme. The use of the purified lipase in the degradation of the residual frying oil showed to be promissory and could minimize various environmental problems.