Kinetic Modeling of Anthocyanin Extraction from Grape Marc

In the present work, kinetic studies of extraction of anthocyanins from grape marc were conducted in order to statistically evaluate several models presented in the literature. Based on a full 2(2) factorial design, extraction was performed using 50 mL of ethanol, at a concentration of 50 %, per gram of dry marc. Extraction was evaluated up to 120 min in the temperature range of 60-25 A degrees C. A pseudo-first-order model provided the best description of extraction of anthocyanins. Yield and rate of extraction increased with increasing processing temperature, varying from 0.906 to 0.476 mg cyanidin 3-glucoside per gram of dry marc and from 0.157 to 0.034 min(-1), respectively, in the temperature range. Results show that the highest yield of extraction happens after 15 min at 60 A degrees C (activation energy of 29.5 kJ mol(-1)), and that after 120 min, thermal degradation has started.