Wine by-products valorisation by green chemistry methods: Impact of the extraction process on the structure, functionalities and activity of the extracted molecules

Abstract

Wine by-products valorisation by green chemistry methods: Impact of the extraction process on the structure, functionalities and activity of the extracted molecules

Viniculture is a huge socio-economic activity throughout the world, 57% of worldwide grape production is for wine-making industry. Wine-making generates huge amounts of by-products (grape pomace (skins, pulp, seeds and stalks), which is around 20 % of total wine production [1]. Wine by-products shown to have a big potential to be used for the extraction of valuable high-added components, however they are sent directly to distilleries for alcohol, spirits and piquette production. The treatment of biomass is often challenging due to its complex matrix

and composition. Heavy industrialization and associated huge environmental impact make reconsidering traditional chemistry methods.

The aim of our work is to valorise valuable components (pectins, fatty acids, polyphenols) from grape by-products by implementing green chemistry methods such as microwave-assisted extraction (MAE), and supercritical CO2 extraction (SFE). In this work, grape pomace from white grapes was considered for the extractions. By using MAE, we were able to extract pectin with a yield up to 8% from grape pomace. Fatty acids were successfully extracted by SFE from grape pomace with CO2 under 40° C, 400 bar and by using ethanol 5% as co-solvent. Water as co-solvent 10 % in supercritical CO2 extraction lead to burgundy coloured liquid, which contained wine related phenolic compounds detected by U-HPLC (gallic and caftaric acids, hydroxytyrosol, catechin). In addition, the coloured extracts undergo pectin isolation procedure and freeze-dried. Initial observation of the extract by FTIR show similar signature to industrial pectin. The findings show possible valorisation of pectin, grape seed oil and phenolic compounds from wine pomace.

[1]        Arvanitoyannis I. S., Ladas D., Mavromatis A., « Wine waste treatment methodology », Int J Food Sci Tech, vol. 41, no 10, p. 1117‑1151, 2006