Study: Tea type influences kombucha properties more than expected

Kombucha has become a widely consumed fermented drink globally. While many choose it for its taste, scientists are increasingly studying the fermentation process. Researchers from Wrocław University of Environmental and Life Sciences and Wrocław Medical University discovered that the type of tea used to make kombucha affects the final product far more than previously thought.

Published in the journal Food Chemistry, the study compared kombuchas made from black, green, white, oolong, and pu-erh teas. "The type of tea acts as a matrix that shapes the fermentation course and the final composition of kombucha," explains Associate Professor Helena Moreira. Different teas vary in polyphenols, catechins, and caffeine content, which are metabolized by SCOBY microorganisms, leading to distinct chemical and aromatic profiles.

During fermentation, yeasts convert sugars into alcohol and carbon dioxide, while bacteria produce organic acids, mainly acetic and gluconic acids, giving kombucha its sour taste. Researchers observed significant changes in polyphenols and volatile compounds affecting aroma. Kombucha showed higher levels of linalool and 2-phenylethanol, associated with floral and fruity scents. Some compounds from fresh tea disappeared, replaced by metabolites from SCOBY.

Green and oolong tea kombuchas exhibited the highest antioxidant activity and free radical neutralization capacity. Free radicals are reactive molecules that can damage cells and contribute to aging. The scientists caution that these results come from lab analyses and should not be interpreted as proof of specific health benefits for humans. "Further clinical studies are necessary to confirm the impact of particular kombucha types on human health," adds Moreira.

The findings also show that kombucha is not a uniform beverage. Green tea kombucha had a fresher, vegetal aroma; oolong kombucha developed stronger floral and fruity notes; black tea and pu-erh kombuchas had richer, earthier aromas with more pronounced fermentation characteristics. The choice of tea is thus a crucial factor in determining kombucha's properties.