Novel insights into flavor formation in whey fermented wine: A study of microbial metabolic networks

In this study, the alterations in the flavor components of whey fermented wine (WFW) were analyzed using gas chromatography–mass spectrometry (GC-MS). Moreover, the changes in the bacterial community structure of WFW were examined using high-throughput sequencing technology. The results showed that the pH value decreased from 5.61 to 3.51 between 0 d and 28 d of fermentation. Meanwhile, the content of total acids (1.31ºT to 7.32ºT), alcohol (8.83%–12.57%), flavonoids (33.98–60.52 mgRE/100 mL), and polyphenols (120.24–230.34 mgGAE/100 mL) increased during fermentation. At the early stage of fermentation, Lactobacillus was the predominant bacterial genus in WFW. However, as fermentation progressed, Lactobacillus and Lactococcus gradually became the dominant genera. Using GC-MS, 102 volatile compounds were identified during fermentation. Among them, 15 substances — including ethyl benzoate, phenyl ethyl acetate, and ethyl butyrate — were identified as the important aroma components of WFW. Fourteen amino acids were detected during fermentation, among which leucine (260.78 μg/L) and tyrosine (250.37 μg/L) showed the highest content. Correlation analysis revealed that Lactococcus was positively correlated with most ester compounds, and Lactobacillus was positively correlated with ethyl phenylpropionate, acetaldehyde, and caprylic acid. Meanwhile, Klebsiella exhibited a significant positive correlation with histidine, aspartic acid, and alanine.