The present study evaluates the effects of açai juice containing gluco-oligosaccharides and dextran, fermented by Bifidobacterium breve NRRL B-41408 (synbiotic juice), on the human fecal microbiota. The juice is subjected to simulated digestion and fecal fermentation after production and 42 days of refrigerated storage. High throughput 16S rRNA sequencing and HPLC are used to identify the bacterial cells and metabolites. The results show that the viability of B. breve is stable during the refrigerated storage, indicating that the metabolism is maintained even under low temperatures and pH. Furthermore, gluco-oligosaccharides and dextran prove to be resistant to gastrointestinal conditions and are quickly consumed during fecal fermentation. The synbiotic açai juice enhances the microbial diversity and stimulates the production of short-chain fatty acids (SCFA), including acetate, propionate, and isobutyrate. Elevated propionate levels are directly associated with an increased abundance of Bacteroides thetaiotaomicron, Bacteroides uniformis, Bacteroides xylanisolvens, Bacteroides dorei, Bacteroides stercoris, and Bacteroides massiliensis after 48 h of fermentation. This highlights the potential of synbiotic açai juice as a functional beverage, supported by the significant increase in microbial diversity reflected in the Shannon and Simpson's diversity indexes (Shannon = 116.6%, 117.2%, 125.15%, and 116.02%; Simpson's = 151.86%, 177.22%, 152.5%, and 163.73%).
Keywords: functional juices; human fecal microbiota; synbiotic açai juice.