+44-7897-074717Luciana Cristina Brigatto Fontes, Elizabeth Aparecida Ferraz da Silva Torres, Lina Yonekura
The aim of this study was to optimize the extraction of antioxidant compounds from guarana and grape pomace using the response surface methodology. A rotatable central composite design was performed to evaluate the extraction efficiency of antioxidants by water-organic solvent mixtures, using two independent variables: water (20-80%) and the acetone:methanol ratio within the organic fraction (0- 100%). Extracts were analyzed for total phenolics, procyanidins and oxygen radical absorbance capacity. The multiple regression analysis and significance test (p<0.05) were realized using the Statistica. The highest total phenolic value from guarana (112.22) was detected at acetone:methanol ratios higher than 70%. Likewise, extraction efficiency of proantocyanidins was optimum (79.41) at higher acetone:methanol ratios, but with lower water percentages in the solvent composition (<29%). The water percentage must be above 80% to give maximum response (4518.79) for ORAC. The optimized conditions that maximized the yields of TP and PC were: water 20% and acetone:methanol ratio 70%, translating into a solvent mixture composed of water:acetone:methanol 20:56:24 (v:v:v). The maximum value of TP from grape pomace (25.36) was detected at acetone:methanol ratios higher than 50% and water percentage lower than 29%. The highest PC value (23.74) was detected at lower water percentages in the solvent composition (<20%). The extracts with maximum ORAC (1493.76) were those resulting from high water percentages and acetone:methanol ratios: 80% and 70%, respectively. The optimized conditions that maximized the yields of TP and PC from grape pomarce were: water 20% and acetone:methanol ratio 50%, translating into a solvent mixture composed of water:acetone:methanol 20:40:40 (v:v:v)
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