Tea Selection Drives Flavor and Health Profile of Kombucha

Kombucha has risen dramatically in popularity across the globe, ranking among the most widely consumed fermented beverages. Although many enjoy it for its unique taste, scientists are increasingly examining the internal changes that occur during fermentation and how the choice of ingredients shapes the final product.

Researchers from the Wrocław University of Environmental and Life Sciences and Wroclaw Medical University—including Associate Professor Helena Moreira, PhD, Associate Professor Ewa Barg, PhD, and Anna Szyjka, MSc Eng.—asked whether the tea variety used to brew kombucha influences the end product. Their results showed far greater variation than anticipated.

The team analyzed kombucha brewed from black, green, white, oolong, and pu-erh teas, publishing their findings in Food Chemistry.

“The type of tea serves as a specific matrix that directs fermentation and determines the final composition of kombucha,” says Associate Professor Helena Moreira, PhD, of the Department of Basic Medical Sciences and Immunology at Wroclaw Medical University. “Each tea varies in its polyphenol, catechin, caffeine, and other bioactive compound contents, which are then transformed by SCOBY microbes. Consequently, fermentation follows distinct pathways, yielding beverages with differing chemical and aromatic profiles.”

How Fermentation Transforms Kombucha

Kombucha is produced when a SCOBY—a symbiotic culture of bacteria and yeast—ferments sweetened tea. Throughout this process, a cascade of complex biochemical reactions occurs.

Yeasts initially convert sugars into alcohol and carbon dioxide. Subsequently, bacteria metabolize these products into organic acids, chiefly acetic acid and gluconic acid, which impart kombucha’s characteristic tartness.

The process also modifies numerous naturally occurring compounds in the tea. Researchers noted alterations in polyphenols, catechins, and volatile substances that influence flavor and aroma.

“Simultaneously, polyphenols and volatile aromatic compounds inherent to the tea undergo transformation. Consequently, the drink develops its signature sour, lightly effervescent flavor and a richer aroma,” explains Associate Professor Helena Moreira, PhD.

The team observed increased levels of compounds linked to floral and fruity aromas, such as linalool and 2-phenylethanol—molecules also present in flowers and essential oils. Meanwhile, several compounds originally found in freshly brewed tea vanished during fermentation, being supplanted by novel metabolites produced by the SCOBY microorganisms.

To investigate these changes in detail, the researchers employed advanced chromatographic techniques coupled with mass spectrometry. This approach allowed them to monitor hundreds of chemical constituents and compare the profiles of kombuchas derived from various tea types.

“The most striking finding was the extent of changes that take place during fermentation and how heavily they depend on the tea variety,” notes the scientist. “Even under identical fermentation conditions, the resulting kombuchas exhibited markedly different profiles of volatile aromatic compounds.”

Green and Oolong Kombucha Exhibit the Highest Antioxidant Activity

The study also indicated that kombuchas prepared from different teas can differ in their biological properties.

Of all the varieties examined, kombuchas brewed from green tea and oolong tea showed the strongest antioxidant activity and the greatest ability to neutralize free radicals.

Free radicals are highly reactive molecules that can harm cells and accelerate aging. Consequently, scientists are actively researching antioxidants and their potential contribution to health support.

“Our findings show that the choice of tea affects not only kombucha’s taste and aroma but also its biological activity,” emphasizes Associate Professor Helena Moreira, PhD. “Notably, kombuchas made from green and oolong teas exhibited the highest biological potential.”

The researchers caution that these results stem from laboratory analyses and should not be taken as evidence of specific health benefits in humans.

“Additional clinical studies are needed to clearly confirm how specific kombucha varieties affect human health,” adds the researcher.

Why the Choice of Tea Matters

Interest in kombucha is growing alongside broader scientific attention to fermented foods. Researchers are increasingly investigating how fermentation can enhance the bioavailability of bioactive compounds, generate novel metabolites, and modulate the gut microbiota.

“Fermented foods now sit at the forefront of scientific inquiry, as they merge traditional techniques with a contemporary perspective on health and nutrition,” states Associate Professor Helena Moreira, PhD. “Kombucha exemplifies a product where chemical composition, biological activity, and sensory characteristics emerge from the intricate interplay between the raw material and the fermentative microbes.”

The findings also underscore that kombucha should not be regarded as a single, uniform beverage. The tea chosen as the base ingredient can substantially affect both its chemical makeup and sensory profile.

Kombucha brewed from green tea tended to exhibit a fresher, more vegetal aroma, whereas oolong-based kombucha developed stronger floral and fruity notes. In contrast, kombuchas made from black tea and pu-erh displayed richer, earthier aromas accompanied by more pronounced fermentation characteristics.

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