Exploring the physico-chemical modification of grape seed extracts to improve their clarifying effect in red wine

Abstract

During winemaking, some byproducts are obtained, such as grape pomace, which represent 13% of winery byproducts [1]. Among grape pomace we can found grape seeds, which have showed promising results in reducing wine turbidity, since they have proteins [2] which interact with turbidity-forming compounds as such polysaccharides [3], polyphenols [4] and other proteins [5] through primarily hydrophobic interactions [6] accelerating their precipitation. However, these seed extracts do not achieve the clarification effect obtained with other commercial clarifying agents frequently used in winery. For that, in this study, white grape seed extracts were enzymatically, physically and chemically modified and applied on a red wine after malolactic fermentation with the objective of verifying if their effectiveness in the clarification process and in the maintenance of wine quality was improved. The determination of turbidity, chromatic parameters and phenolic content, carried out in wines after a period of contact with different clarifiers, showed that extracts treated with cellulase, ultrasounds and HCl improved its performance in comparison with grape seed extract without treatment, the results being very similar to that obtained with commercial clarifying agents commonly used in wineries. It is clear that some of the treatments carried out on grape seed extracts produced important changes at structural and composition level, making them more reactive and improving their clarifying capacity without affecting red wine quality. Their implementation as new clarifying agents in wine industry would promote the circular economy in the oenological sector.

References

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[6] Marangon, M., Marassi, V., Roda, B., Zattoni, A., Reschiglian, P., Mattivi, F., Moio, L., Ricci, A., Piombino, P., Río Segade, S., Giacosa, S., Slaghenaufi, D., Versari, A., Vrhovsek, U., Ugliano, M., De Iseppi, A., Marangon, C., Curioni, A. (2024). Food Res. Int., 187, 114414.