Kinetics and thermodynamics characteristics of microwave assisted extraction of anthocyanins from grape peel

In order to expand the application of microwave assisted extraction (MAE) in food industry, the effects of MAE of anthocyanins from grape peel was investigated, and the related kinetics and thermodynamics were evaluated. The results showed that the citric acid concentration, liquid-to-solid ratio (RL/S), extraction time and microwave power level have a significant influence on the anthocyanins yield. The anthocyanins yield (172.99 mg/100 g) with the higher concentration of citric acid solution (1.00 mol/L) is 4 times larger than that (43.48 mg/100 g) in the lower concentration solution (0.02 mol/L). Furthermore, the extraction kinetic analysis indicated that the exponential decay model is the best model to fit the experimental data of anthocyanins obtained from MAE in this study (R2>0.9875). The effective diffusivity value of anthocyanins (2.12~4.87×10-11 m2/s) was enhanced concomitantly with increasing values of microwave power level in MAE process. The thermodynamic parameters of MAE indicated that microwave irradiation benefit the mass transfer. The result can provide a reference for industrial production of MAE.