Lipase from Candida rugosa incorporated in pectin hydrogel via immobilization for hydrolysis of lipids in dairy effluents and production of fatty acids

Pectin-based hydrogels containing immobilized Candida rugosa lipase were applied in the pretreatment of dairy effluents using Box-Behnken experimental design. In this context, tests were performed for the determination of the point of zero charge of the hydrogel, activity of the free enzyme in solution and immobilized on the solid support, reuse stability and operational stability of the free and immobilized enzyme, hydrolysis efficiency of the free and immobilized enzyme in a simulated synthetic effluent and real effluent, along with analyses of BOD5, COD, turbidity and pH of the effluent samples before and after pretreatment steps. Fourier-transform infrared spectra and thermogravimetry curves confirmed support functional groups and thermal resistance, respectively. Response surfaces revealed that the lipase immobilization capacity increased at temperatures close to 25 C-degrees, an initial enzyme concentration of 4.0 mg mL(-1) and pH close to 8.0. Significant storage stability was found of the immobilized enzyme and greater hydrolysis was found in the simulated synthetic effluent with both the free and immobilized enzyme compared to the real effluent of the dairy industry. Greater hydrolysis efficiency occurred after 120 min, with approximately 69.2 % +/- 0.5 of free fatty acids produced. According to the degradability level, a biological pathway is more indicated than physical methods for degrading lipids, considering the composition of effluents from dairy industries.