Quantification of polysaccharides of variety Pomaces of the D.O.Ca Rioja

Abstract

Pomace is one of the main residues generated by the wine industry and represents an environmental problem. Currently, there is a growing interest in the revaluation of these products because different bioactive compounds can be obtained from them, such as polyphenols, grape seed oils and polysaccharides. Red grape pomace can be an important source of polysaccharides, but they are currently little studied and even less with viable and environmental extraction processes (green extraction), such as flash extraction. The residual amount of the fraction rich in pectin (residual pulp) and component rich in hemicellulose in the pomace and the strength of association of the pectin with the cellulose-xyloglucan network depend on the degree of extractability of the polysaccharides in red winemaking and on the winemaking conditions. The extractability of the polysaccharides increases with the maturity of the grape and, with the same degree of maturation, the extractability of the polysaccharides depends on the grape variety used. In this work, the distribution of molecular weights was studied and the polysaccharides of varietal pomace of Vitis viniferaL cv Tempranillo, Garnacha, Graciano, Maturana tinta and Mazuelo (varieties admitted by the D.O.Ca Rioja) extracted by the flash extraction technique with the objective of selecting the variety with the highest residual amount of polysaccharides in the pomace. The red vinification method was the traditional one and the degree of maturation of the grapes was similar for all the varieties. The results show that there are significant differences in the total content of pectic families among the five varieties. The estimated content of polysaccharides with a molecular weight greater than 5000 Da was similar for the pomace of Tempranillo and Garnacha, while those of Mazuelo and Maturana were lower.

Acknowledgments: This research was funded by the Ministry of Science, Innovation and Universities from the Spanish Government and Feder Funds, grant number PID2021-123361OR-C22.