From microbial communities to aroma profiles: A comparative study of spontaneous fermentation in merlot and cabernet sauvignon wines

This study aimed to compare the microbial community composition and aroma characteristics during the fermentation of different grape cultivars, Merlot and Cabernet Sauvignon. Principal Component Analysis (PCA), Partial Least Squares Discriminant Analysis (PLS-DA), and Odor Activity Value (OAV) screening identified 15 distinct active compounds. The sensory evaluation indicated that Merlot wine exhibited a more intense fruity aroma and received higher overall scores than Cabernet Sauvignon wine. High-throughput sequencing (HTS) results revealed that the microbial diversity in Merlot was higher than in Cabernet Sauvignon wine. <i>Lachancea</i>, <i>Acremonium</i>, <i>Fructobacillus</i>, and <i>Lactiplantibacillus</i> were unique to the Merlot wine, whereas <i>Penicillium</i>, <i>Wickerhamomyces</i>, <i>Gluconobacter</i>, and <i>Klebsiella</i> were exclusive to Cabernet Sauvignon wine. <i>Saccharomyces</i> and <i>Tatumella</i> were identified as the dominant microorganisms during the fermentation of both Merlot and Cabernet Sauvignon wines. Correlation analysis demonstrated a significant positive association among the dominant microbial communities, which played a crucial role in determining the formation of volatile compounds.