Fermentation of native Brazilian fruits with kombucha: A novel opportunity for producing low-alcohol beverages

The biodiversity of Brazil includes native fruits such as red-araçá, butiá-da-serra, and jaboticaba, which are rich in bioactive compounds. Promoting the use of these fruits can help preserve them and provide consumers with new healthy beverage options. This study used kombucha as an inoculum to ferment pulp from these native fruits, and the resulting beverages were evaluated for their physicochemical properties, substrate consumption, metabolite production, total phenolic content, antioxidant activity, and microbial composition over 10 days. A correlation was made between substrate consumption, metabolite production, and the most abundant microorganisms. During fermentation, pH decreased, and total titratable acidity increased in all samples. Total soluble solids were reduced in the red-araçá and jaboticaba samples. Sucrose was hydrolyzed into glucose and fructose, and both reducing sugars were metabolized by microorganisms as fermentation progressed. Ethanol ranged from 0.1 to 0.7 (% v/v), acetic acid from 0.19 to 6.12 g/L, and glycerol from 0.03 to 0.64 g/L. A significant increase in total phenolic content was observed in the red-araçá and jaboticaba beverages from day 5, with red-araçá exhibiting the highest antioxidant activity, exceeding 500 μmol TE/100 mL. Predominant microorganisms identified through shotgun sequencing included yeasts Brettanomyces anomalus and Zygosaccharomyces sp., and bacteria Gluconobacter oxydans, Komagataeibacter rhaeticus, and K. saccharivorans. Correlation analysis showed that metabolite production helped inhibit competing microorganisms and potential pathogens, ensuring the beverages' safety. These results demonstrate the potential for developing low-alcohol, low-sugar fermented beverages with functional benefits from native fruits.