Fermented fruit state shapes flavor quality and methanol accumulation in kiwi wine: A comparative study of three flesh-colored kiwifruit cultivars.

The fermented fruit state represents a critical processing variable that simultaneously governs flavor development and methanol accumulation in fruit wine. In this study, three kiwifruit cultivars differing in flesh colors were fermented under four fruit states (peel presence/absence and pulp maceration/juice fermentation), following a 3 × 4 factorial design. Relative to juice fermentation, pulp maceration reduced total acidity and elevated total phenolic and flavonoid contents. A total of 130 volatile compounds were identified across all treatments, with alcohols and esters as the dominant classes. Pulp maceration generally favored ester accumulation and fruity and floral aroma attributes, whereas peeled or juice-fermented wines were characterized by higher contributions of volatile alcohols. Methanol accumulation increased with pulp maceration, and was accompanied by greater water-soluble pectin consumption, higher total pectin degradation, and elevated pectin methylesterase activity. Cultivar background further modulated these responses. These findings provide a practical basis for kiwi wine fermentation strategies.