Elaboration and Characterization of Novel Kombucha Drinks Based on Truffles ( Tuber melanosporum and Tuber aestivum ) with Interesting Aromatic and Compositional Profiles.

The organoleptic and bioactive properties of truffles place these fungi as interesting materials for use in the of design functional foods based on fruiting bodies outside commercial standards. Moreover, kombucha beverages have become more popular in the Western world, leading to novel drinks using alternative substrates instead of tea leaves. In this work, two truffle species ( Tuber melanosporum , TMEL; Tuber aestivum , TAES) and three different symbiotic consortia of bacteria and yeasts (SCOBYs: SC1, SC2, and SC3) were tested. Fermentation (21 days) was monitored in terms of physicochemical (pH, viscosity), biochemical (total carbohydrates, alcohol, soluble proteins, phenolic compounds), and sensory attributes (volatile organic compounds, VOCs). The obtained pH ranges were adequate, alcohol levels were undetectable or very low, and sugar content was lower than in traditional kombuchas or other beverages. In most cases, the usual bottling time could be applied (7-10 days), although longer fermentations are recommended (14 days) to reach higher protein and phenolic compounds contents. Truffle kombuchas produced up to 51 volatile organic compounds (alcohols, acids, esters, ketones, and aldehydes, among others), with TMEL showing a more complex profile than TAES. During the first week, acidic compound production was observed, especially acetic acid. Similar behavior in the VOC profile was reported with different SCOBYs.