Effects of Wine Yeast Preadaptation on Alcoholic Fermentation Performance and Wine Metabolic Profiles

Background: The physiological condition of wine yeasts before inoculation influences their tolerance to fermentation-related stresses, metabolic activity, and fermentation performance. Evidence remains difficult to interpret because physiological conditioning is often considered alongside rehydration, supplementation, and adaptive evolution. This review aims to determine under which conditions controlled preadaptation supports fermentation completion and modifies wine metabolic profiles, and whether improvements in cellular protection translate into technological and sensory benefits. Methods: A narrative review with a qualitative appraisal of evidence directness and interpretive limitations was conducted, focusing on osmotic, thermal, and ethanol conditioning, stepwise acclimation, stress-response mechanisms, and metabolite formation. Physiological preadaptation was distinguished from rehydration, nutrient supplementation, starter propagation, and adaptive laboratory evolution. Experimental findings were evaluated according to yeast strain, conditioning conditions, fermentation performance, and metabolic outcomes. Results: Direct pretreatment evidence in wine yeasts remains limited and strain dependent. Mechanistic studies implicate glycerol regulation, trehalose, membrane remodelling, antioxidant defence, and chaperones, but do not independently establish conditioning efficacy. These responses depend on strain characteristics, conditioning intensity and duration, and the persistence of induced protection. Improved viability or shorter lag phases do not necessarily ensure complete glucose and fructose utilisation or favourable wine composition. Potential changes in glycerol, organic acids, higher alcohols, esters, carbonyls, and sulfur compounds require consideration of the overall fermentation environment. Conclusions: Controlled preadaptation is a candidate strategy for defined strain–process combinations; the evidence does not support a species-wide benefit or a universal protocol. Establishing its technological value requires controlled comparisons that distinguish physiological conditioning from nutritional and biomass effects, alongside validation of fermentation completion, metabolic composition, and sensory quality.