Chemical, microbial, and functional characterization of a new fruity probiotic kombucha

This study aimed to evaluate the effect of adding Lacticaseibacillus casei as probiotic culture and/or camu-camu (Myrciaria dubia) pulp on the chemical profile, technological, functional, and sensory properties, phenolics concentration and bioaccessibility, and microbiota of kombucha. Adding L. casei decreased some volatile compounds and fruity flavor intensity and increased the Lactobacillus relative abundance (+35.73 %) and lactic acid content (from 1.26 to 1.54 g/L), decreasing flavor and overall impression acceptances. Adding camu-camu pulp resulted in more acidic products (pH of 2.75 vs 3.24), with a higher concentration of some phenolic compounds. The kombucha with L. casei and camu-camu pulp was characterized by a higher concentration of citric and acetic acids, ethanol, ascorbic acid, and most of the phenolic compounds and volatile compounds, higher bioaccessibility of phenolic compounds, increased consistency index, improved functional properties (inhibition of α-glucosidase and antioxidant activity), and better sensory properties. Furthermore, it showed an increased relative abundance of Lactobacillus (+15.11 %) and a decreased relative abundance of Acetobacter (-5.56 %) and Komagataeibacter (-9.12 %) compared to the conventional kombucha. L. casei survived the processing (> 7 log CFU/mL) and simulated gastrointestinal conditions (>5 log CFU/mL). In conclusion, the association of L. casei and camu-camu pulp resulted in potentially probiotic kombuchas with improved chemical profile, functional, technological, and sensory properties, phenolic compounds concentration and bioaccessibility, and bacterial microbial diversity.