Compositions and chemical variability of grape pomaces from French vineyard
Résumé
Compositions of 8 pomace samples originating from red and white winemaking from different areas of production of French vineyard were characterized (Alsace, Bordeaux, Bourgogne, Champagne, Languedoc, Val de Loire and Provence). Large variabilities were observed depending on cultivar and grape varieties: pomace samples contained 3-6% w/w of oil and 20-46% w/w of sugars, mainly glucans and xyloglucans with a relatively low pectinaceous polysaccharides content. Condensed tannins accounted for 20-51% w/w and can be extracted in an aqueous medium. The reactivity of some of these extracts toward formaldehyde (through gel time analysis) demonstrated their promising properties for adhesive applications. The results obtained in the present study confirm that grape pomace constitutes a promising source for a valuable utilization of this by-product.