Biosorption of anthocyanins from grape pomace extracts by waste yeast: kinetic and isotherm studies

The potential uses of two food industry by-products were analyzed in this study. The extraction optimization of anthocyanins from grape pomaces of different grape varieties and the application of waste brewery's yeast biomass as biosorbent of the anthocyanins in solution were evaluated. The biosorption capacity of the biomass was determined by pseudo-second order kinetic model and different isotherm models were used to describe the biosorption process. Fourier Transform Infrared Spectroscopy (FTIR) analysis was carried out to characterize the interaction of the biomass with anthocyanins. The biosorption process was also evaluated by HPLC analysis. Experimental data of the isotherm profile were adequately described by the Temkin model. The mean free energy (E) value from the model of Dubinin-Radushkevich suggested the occurrence of a chemical mechanism in the biosorption process. FTIR absorption spectrum of yeast biomass was complex. Significant changes in the intensity of yeast cell absorption bands and shifts of characteristic bands were observed after biosorption.