Evolution of flavor metabolites and microbial communities during aging of spontaneously fermented and inoculated wines from different viticultural systems

Natural wines are valued for complex flavors and terroir expression, yet the mechanisms underlying flavor and microbial dynamics during aging remain unclear. This study compared spontaneously fermented and inoculated wines produced under conventional management and extra-simplified eco-viticulture, with emphasis on dynamic changes in flavor metabolites, microbial communities, and biogenic amines during aging. The results showed that Kazachstania humilis , Aureobasidium pullulans , and Oenococcus oeni predominated in spontaneously fermented wines throughout the aging process. In contrast, inoculated wines were initially dominated by Saccharomyces cerevisiae and Oenococcus oeni , followed by Burkholderia spp. Spontaneously fermented wines were characterized by higher concentrations of ethyl acetate, ethyl lactate, phenylethyl acetate, and phenethyl alcohol, whereas inoculated wines were enriched in ethyl caproate, ethyl caprylate, ethyl decanoate, methionol, and isovaleric acid. Moreover, various phenolic acids and their derivatives increased during aging, while certain flavonoids decreased. Biogenic amines, mainly tryptamine and putrescine, exhibited an overall increasing trend. Overall, spontaneously fermented wine from extra-simplified eco-viticulture (ES-S wine) showed more stable and distinctive flavor profiles with superior sensory quality, while spontaneously fermented wine from conventional management (CM-S wine) exhibited inferior quality. These findings provide insights into the maturation and stabilization of natural wines and support the optimization of natural winemaking practices. • First application of PacBio SMRT sequencing to identify microbes in wine aging. • Flavor evolution during aging was analyzed in spontaneous and inoculated wines. • Biogenic amines were monitored during wine aging to evaluate wine safety.