PRODUCTION OF GRAPE POMACE EXTRACTS WITH ANTIOXIDANT PROPERTIES: A STUDY BASED ON PROCESS OPTIMIZATION BY EXPERIMENTAL DESIGN

This work evaluated the effects of different process parameters on recovery of antioxidant compounds from grape pomace (GP), using a Central Composite Design (CCD). The results obtained showed that the increase in the pectinase concentration applied in GP promoted a positive effect on the obtaining of extracts with best antioxidant properties evaluated by DPPH-radical scavenging, while the shortest reaction time positively affected the antioxidant activity measured by ABTS+ method. Increase in temperature leads to an increase in all responses. As for the increase in pH solution, there was an increase of antioxidant capacity by the DPPH and ABTS+ methods and a decrease by the FRAP. The best conditions for process optimization in order to increase the antioxidant properties of the extracts were found in the GPS treated with 2% pectinase, an incubation time of 1 hour, at 50 °C and pH 5. At these conditions, predicted values of antioxidant capacity determined by the ABTS+, DPPH and FRAP methods were 79.5, 24.2 and 108.9 μmol Trolox Equivalent per gram of dry GP, respectively. GPs exhibited strong antioxidant capacity, representing a source of bioactive compounds in obtaining functional ingredients in the food industry.