Non-ionic surfactants-mediated green extraction of polyphenols from red grape pomace

Abstract

Around 80% of grape production is towards winemaking, generating large amounts of polyphenol-rich waste. Conventional techniques, commonly employed in polyphenols extraction from grape pomace, are often environmentally unfriendly or time and energy-consuming. Green surfactant-based extraction of polyphenols has not been thoroughly investigated for the utilization of red grape pomace. This study aimed at investigating the potential of eleven non-ionic surfactants belonging to poloxamer, Brij, Triton, and Tween subgroups. Aqueous solutions of surfactants in different concentrations and variable solvent-to-material ratios were investigated. The extraction efficiency was evaluated through quantification of individual phenolic compounds, total phenolic content, and antioxidant activity. Generally, surfactants with longer oxyethylene chains provided greater efficiency (Brij S20 and poloxamer 407). It has been shown that surfactants' chemical structure affects the solubilization mechanism of polyphenols. Extraction rate depended on concentration and solvent-to-material ratio, as well. The dominant phenolic compounds in extracts were quercetin and catechin. Investigated non-ionic surfactants aqueous solutions have been shown as effective mediums suitable for low-cost and straightforward extraction of polyphenols and for obtaining extracts with a favorable phenolic profile.