Hydrothermal treatment of grape skins for sugars, antioxidants and soluble fibers production

The valorisation and the reuse of agricultural residue and food waste are gaining more attention in the last years as are directly related to environmental sustainability. For this reason, the aim of this study is to evaluate the influence of autohydrolysis operating conditions for a high yield recovery of sugars, soluble fiber and antioxidants from grape skins. In this work, an experimental campaign using a lab-scale batch autohydrolysis reactor is scheduled based on statistical methods to assess the influence of some process variables (like water to skins solids ratio or working temperaure) on some selected key performance indicators (KPIs), like sugars, sugar degradation products, phenolic compounds, antioxidant compounds and fiber recovery. As a comparison, different agricultural residue, like wheat straw, are considered. Entering in the details, the volume of the recovered autohydrolysis liquid fraction is measured and analyzed to calculate the release yield of both total solids and specific components, including antioxidant activity according different in vitro assays tests such as and ABTS assay. Therefore, this work presents an innovate autohydrolysis process for the valorization of waste grape skins for the production of added-value compounds through a potentially green technology.