First trials to assess the feasibility of grape seed powder (GSP) as a novel and sustainable bentonite alternative.

Grape pathogenesis-related proteins can cause haze in wine that is undesirable for consumers. Bentonite is used to remove these proteins but is a non-renewable natural material and reduces wine volume due to poor settling. As a potential bentonite alternative, grape seeds powder (GSP) was added to four wines and two grape juice varieties. Addition to wine required high doses (25-32 g/L) for protein removal and haze prevention and this induced changes to wine composition. By contrast, addition to grape juice prior to fermentation required substantially lower doses of GSP (5 g/L) to prevent haze formation. Further 20 g/L of GSP added to the must induced less changes to wine composition than direct addition of GSP to the wine. No changes were recorded in the efficacy of protein removal by changing the GSP source (red or white grape marc), or by using grape seed roasting. Despite the need for additional trials, these preliminary results suggest that GSP may be considered as a viable alternative to bentonite especially when added to juice prior to fermentation.