Exploring the functional, aromatic and metabolomic profile of kombucha beverages based on edible mushrooms

Kombucha is a fermented beverage traditionally produced with tea leaves and sugar, but the use of alternative substrates has gained increasing attention due to their potential to enhance nutritional and sensory properties. In this study, commonly consumed and commercially available edible mushrooms in Europe-Agaricus bisporus, Pleurotus ostreatus, Pleurotus eryngii, Lactarius deliciosus, Cantharellus cibarius, and Boletus edulis-were employed as substrates for kombucha fermentation using three different SCOBY (Symbiotic Culture of Bacteria and Yeasts) consortia. Fermentations were monitored for 21 days, assessing pH, total soluble solids, ethanol, soluble proteins, and total phenolic compounds. Across all mushroom substrates, sugar depletion and acidification occurred, while protein and phenolic contents varied depending on mushroom type and SCOBY used. Agaricus bisporus based kombucha showed the most distinctive aromatic profile. The analysis of major volatile compounds indicated that differences were mainly associated with the SCOBY used rather than with the fermentation matrix. Preliminary metabolomics analyses highlighted substrate-driven differences in fermentation outcomes. Overall, mushroom kombuchas demonstrated low residual sugar, enhanced protein levels, and complex aroma profiles, supporting their potential as novel functional beverages.