Industrial byproducts valorization through energy saving processes. Alkaline extraction of polyphenols from vine shoots

Vine shoots are viticulture byproducts recently valorized as important sources of polyphenols. These are powerful natural antioxidants used in several industrial applications. The aim of this work is to intensify polyphenol extraction from vine shoots (Syrah variety) using energy saving techniques. In this study, we chose to work with green solvent and in absence of organic solutions. The effect of NaOH concentrations (0, 1, 10, 100 and 1000 mM) on polyphenol extraction was studied. Polyphenol concentrations (Folin-Ciocalteu) and diffusion coefficients (Fick´s second law) were calculated. The radical scavenging activity (DPPH assay) of extracts was determined. Polyphenol identification and quantification were conducted by High Performance Liquid Chromatography (HPLC). The maximal polyphenol yield (5 mg GAE/g of dry matter (DM)), diffusion coefficient (9 × 10^-12 m²/s), radical scavenging activity (62 %) and the maximum molecular diversity were obtained using 1000 mM NaOH solution. We hereby propose an environmentally friendly procedure to valorize industrial waste using green technology, leading to the recovery of target compounds and their recycling inside food chain.