Cross-flow filtration of lees grape juice for non-aromatic white wine production: a case study on an Italian PDO

Abstract

During white winemaking, after clarification, a considerable amount of juice remains trapped in the lees. Recently, cross-flow filtration has become popular to recover a large amount of juice from lees. However, high juice recovery is observed to be consistent with a decrease in wine quality, while low recovery reduces the amount of wine that can be produced. Therefore, this study aims to find the optimal compromise between quantity and quality. We tested at industrial scale and in three replicates, qualitative changes in an elite Italian white wine as a function of different amounts of juice recovered. The length of the filtration cycle affected the juice’s chemical parameters. In some cases, uncontrolled alcoholic fermentation started before the yeast inoculum, leading to a small increase in ethanol, and higher acetic acid and ethyl acetate concentrations that can be find in the resulting wines. The phenomenon was particularly apparent in longer fermentation cycles. Furthermore, longer filtration cycles increased juice acidity and potassium, while the resulting wines changed in terms of pH, glycerol, and volatile profile. Several grape-related compounds were found in wines at different concentrations as a function of the amount of juice recovered. In particular, Z3-hexen-1-ol, p-cymene, β-ionone, and benzyl alcohol were found to increase, reaching a maximum at 65% of recovered juice before decreasing. Furthermore, several fermentation-related compounds were found to change according to the length of the filtration cycle. Our work identifies an optimal recovery point of 65%. This percentage appears the best trade-off between the flavor of wines, fermentation risk management, and the amount of juice recovered.