Abstract
Extensive research has been dedicated to elucidating the role of various nitrogen sources, nitrogen concentrations and the timing of addition when modulating grape must fermentation using yeast. The wine industry invests substantial resources in both the vineyard and the winery to provide adequate nitrogen concentrations for fermentation. This approach ensures optimal yeast performance during fermentation and minimises the risk of negative sensory attributes associated with poor ferment nutrition. In addition to wine, the winemaking process produces a substantial quantity of nutrient-rich biomass, a poorly explored resource that, if appropriately recycled, could be used to support the nutrient requirements of other winery fermentations. This study explored the feasibility of using processed yeast lees generated during alcoholic fermentation as a nutrient supplement in subsequent fermentations. Three lees treatment options were assessed: accelerated autolysis, enzymatic lysis and mechanical lysis. The ability of these treatments to achieve complete lysis of yeast cells and release amino acids and trace elements is reported. The addition of processed lysates into grape juice was shown to improve fermentation timeframes and influence the production of yeast-derived fermentation volatile compounds in a dose-dependent manner. This study demonstrates that recycling spent lees from winery waste is feasible and provides some strategies for extracting nutrients from winery waste.