RECOVERY OF ANTHOCYANIN FROM WINE LEES USING PRESSURIZED LIQUID EXTRACTION AS AN ECO-FRIENDLY APPROACH

The recovery of anthocyanins from winery by-product has attracted much attention, due their important role in the food industry, both as natural colorants and as functional ingredients. Wine lees are an underexplored by-product found in the wine process and studies showed that the concentration of anthocyanins is 10 times higher than in grape skins. This study aimed to recover the anthocyanin-rich extract from wine lees by pressurized liquid extraction (PLE). PLE was employed at 100 bar, for 5 minutes and a central composite design was used to assess the effects of acidified ethanol concentration (30, 50, and 70%) and temperature (40, 55, and 70°C). The statistical significance of the factors was analyzed by ANOVA (confidence intervals at 95% level), and the adequation and fit quality of mathematical models built were checked by p-lack of fit and determination coefficient (R2). Total monomeric anthocyanins(TMA) measurements were performed by pH differential method and results were expressed as mg/g (dry basis). The experimental results obtained by PLE showed a significant difference (p < 0.05) and anthocyanin content ranged from 2.13 to 3.85 mg/g. The resulting models did not show a lack of fit (p > 0.05) and explained 85% of the variance. According to the proposed models, the temperature quadratic effect contributed negatively and significantly to the anthocyanins response, meaning a maximum extraction rate exists. Significant linear and quadratic effects of solvent concentration were found for wine lees anthocyanin extraction in the studied range. Then, the optimal condition for TMA extraction was obtained at 55°C, with 58% ethanol (3,8 mg/g). Therefore, the green extraction process (PLE) applied on wine lees, seems to be a promising and challenging route to achieve new valuable bioactive compounds, according to a circular economy approach.