In Vitro Gastrointestinal Digestion and Gut Fermentation of Atlantic Forest Fruit‐Flavored Kombucha: Gut Microbiota Dynamics and Bioactive Compound Bioaccessibility

ABSTRACT Fermented foods are sources of highly bioavailable nutrients and compounds with health benefits. This exploratory study evaluated compound bioaccessibility, microbial survival and the effects of kombucha with Atlantic Forest fruits (jaboticaba, grumixama, juçara) on gut microbiota in healthy individuals. Samples underwent simulated digestion and 24 h fermentation with human fecal microbiota. Microbiota composition was analyzed by 16S rRNA amplicon sequencing, and SCFAs and BCFA were quantified. Yeasts, acetic acid bacteria, and lactic acid bacteria remained viable after digestion. Flavored kombucha (FK) showed high antioxidant activity. After 24 h, SCFAs increased, particularly acetate in FK; natural kombucha showed moderate effects, while tea and commercial kombucha caused minimal changes. Time was a major driver of variation in alpha and beta diversity, with the former declining especially with FK. The main taxonomic shifts included an increase in Enterobacteriaceae and a reduction in some beneficial taxa, with formulation‐dependent specific modulation.