Impact of winemaking technologies on polyphenolic composition and wine microbiome

Introduction This study investigates how different oenological practices, including spontaneous and inoculated alcoholic fermentation (AF), variations in malolactic fermentation (MLF) and ageing, are associated with changes in microbial diversity and polyphenolic profile of Sauvignon blanc wines. Methods Microbial composition was investigated through high-throughput DNA sequencing, while polyphenolic compounds were analysed using LC–MS together with total phenolic content through Folin–Ciocalteu assay and antiradical activity by DPPH assay. Results and discussion AF was associated with a pronounced homogenization of the microbiota, particularly through the dominance of Saccharomyces and stable epiphytic bacteria. At later stages, microbial communities showed notable compositional divergence, with their development closely linked to technological interventions and the extent of phenolic extraction. The pomace-fermented treatment exhibited the highest polyphenol content along with the greatest compositional heterogeneity, whereas treatments with lower phenolic loads exhibited simpler microbial profiles and the stable dominance of Leuconostoc after malolactic fermentation. Polyphenols appear to act as modulatory factor in microbial succession, with extraction intensity showing a more distinct association with community shifts than the fermentation regime itself. Overall, the study highlights that technological practices affecting phenolic extraction appear to play a notable role in the observed microbial trends and the resulting wine characteristics.