Dynamics of microbial communities, flavor, and physicochemical properties of kombucha-fermented Sargassum fusiforme beverage during fermentation

In this study, a novel kombucha-fermented Sargassum fusiforme beverage was prepared, and physicochemical properties, volatile flavor compounds, and microbial communities during the beverage fermentation were investigated. The results indicated that after fermentation, the pH decreased to 2.77 ± 0.05, titratable acid content increased to 4.42 ± 0.20 mg/mL, organic acids content increased and acetic acid became the main organic acid, values for total sugar content decreased and the reducing sugar content increased during fermentation. The clearance rates of DPPH radicals, hydroxyl radicals, superoxide anion radicals, and ABTS radicals increased after fermentation. In addition, the results of high-throughput sequencing showed that Zygosaccharomyces was the main fungi, and Komagataeibacter and Acetobacter were the main genera of bacteria in kombucha-fermented S. fusiforme beverage. Gas chromatography-ion migration spectrometry results showed that ethanol, acetic acid, acetone, and ethyl acetate were the main volatile flavor compounds. The correlation results between the dominant microbial community and the major volatile flavor compounds indicated that Pichia, Aspergillus, Zygosaccharomyces, Acetobacter, and Ralstonia had a positive effect on the flavor formation of beverages, which provided the direction for the later development and accurate screening of flavorous functional microorganisms.