Natural Aromatization of Green Tea Infusion by Fermentation with Edible Basidiomycetes – Flavor Tuning towards Hedonic Western Flavors

In response to the increasing interest of western consumers in the nutritional value of green tea but their low acceptance of its green odor, basidiomycetes were employed as innovative starter cultures to tune flavor of green tea infusion. This study revealed that a simple and short one-step fermentation with selected basidiomycetes well shifted the original green tea flavor towards interesting and hedonic flavors. Elucidation of key aroma compounds revealed methyl jasmonate, beta-ionone, (E,E)-2,4 decadienal as well as 2-ethyl-3,5-dimethylpyrazine to be responsible for the overall chocolate-like aroma impression produced by F. velutipes. Elucidation of key aroma compounds after M. scorodonius fermentation revealed a different pattern of aroma compounds (dihydroactinidiolide, isovaleraldehyde, and coumarine) to be responsible for the flavor shift. Both findings revealed for the first time that basidiomycetes can synthesize alkylpyrazines, however the biosynthesis pathway including intermediates and enzymes is not clear so far. The third chosen combination of green tea with W. cocos exhibited an appealing floral, jasmine like and slightly citrus-like beverage with original green-tea bitterness and astringency attributed to methyl anthranilate, linalool, 2-phenylethanol, and geraniol. Elucidation of the catechin profile showed reductions in a range up to -50% compared to original catechin concentrations. Nevertheless, in vitro antioxidant capacity revealed still 80% of the original antioxidant capacity being present after fermentation. Overall, the potential of the novel approach for tea beverages aromatization was successfully confirmed with three edible basidiomycetes. New tea-based beverages with pleasant flavors tailored for the European and Western market could be achieved.