A Wrocław team compared kombuchas brewed from black, green, white, oolong, and pu erh teas. Green and oolong led on antioxidant activity, and the mechanism behind that ranking tells a clearer story than the ranking itself.
Most kombucha drinkers pick their base tea by habit, by what the grocery store stocks, or by what the bottle label says. A new peer-reviewed study from two Wrocław universities argues that choice is the dominant variable in the cup. The team brewed kombucha from five different teas under controlled conditions and ran each batch through the same chemical and biological assays. The result, according to the institutional press summary on SciTechDaily, is that green and oolong teas produced kombuchas with the strongest antioxidant activity, while every tea type left its own fingerprint on the final drink's chemistry and aroma.
The study, published in Food Chemistry, was led by Assoc. Prof. Helena Moreira, PhD, and Assoc. Prof. Ewa Barg, PhD, of Wrocław Medical University, with Anna Szyjka, MSc Eng., of Wrocław University of Environmental and Life Sciences, on the team. The premise was simple but rarely executed cleanly: take five teas, ferment each under the same conditions with the same SCOBY (the symbiotic culture of bacteria and yeast that drives kombucha fermentation), and compare what comes out.
Why tea type matters comes down to what tea is, chemically, before fermentation touches it. Black, green, white, oolong, and pu-erh are all made from the same plant, Camellia sinensis, but they differ sharply in their polyphenol and catechin content, in caffeine levels, and in the smaller aroma compounds that survive into the leaf. The SCOBY metabolizes those inputs. Yeast cells convert sugars into alcohol and carbon dioxide; bacteria then convert those into organic acids, primarily acetic and gluconic acids, which give kombucha its tartness. What is less obvious is that the microbial community also transforms tea-specific compounds into new metabolites, some of which were never in the leaf to begin with.
As Moreira put it in the SciTechDaily summary, "The type of tea acts as a specific matrix that shapes the course of fermentation and the final composition of kombucha." In other words, the tea is not a passive backdrop. It sets the chemistry the SCOBY has to work with, and the microbes respond differently to each input.
The research team used advanced chromatography and mass spectrometry to track and compare hundreds of compounds across the five tea-type kombuchas. They found significantly higher levels of floral and fruity aroma compounds, including linalool and 2-phenylethanol, in some of the brews. Compounds that are typical of freshly brewed tea disappeared entirely and were replaced by new SCOBY-produced metabolites. Each tea gave the kombucha a distinct chemical and aromatic profile. None of the five produced a generic kombucha.
The comparative headline finding, also from the SciTechDaily summary of the study, is that kombuchas made from green and oolong teas showed the strongest antioxidant activity and the greatest ability to neutralize free radicals in vitro. Moreira's framing in the same summary is direct: "The results of our research indicate that the type of tea influences not only the taste and aroma but also the biological activity of kombucha. Particularly interesting results were obtained for kombuchas prepared from green and oolong teas, which demonstrated the highest biological potential."
The mechanism behind that result tracks with what is already known about these teas. Green and oolong sit at intermediate oxidation levels, and both retain a high proportion of catechins and other polyphenols that survive into the brew and that the SCOBY can further transform. Black tea, fully oxidized, starts with a different polyphenol profile. White and pu-erh each bring their own chemistry, and the study documents how those starting points cascade through fermentation.
Two things the study does not claim are worth naming. The antioxidant activity was measured in the lab, in cell-free chemical assays, not in people. The researchers' own caveat, included in the SciTechDaily summary, is explicit: "Further clinical studies are necessary to clearly confirm the impact of particular types of kombucha on human health." The study characterizes kombucha's chemistry and in-vitro bioactivity. It does not, and should not be read as, a health-outcomes trial.
There is also a second-order point sitting underneath the ranking. Kombucha is part of a broader scientific interest in fermented foods because fermentation can increase the availability of bioactive compounds, create new metabolites, and influence the gut microbiome. The Wrocław study is one of the cleaner data points in that literature, in that it controlled the fermentation and varied a single input, the tea. That control is what makes the result useful to anyone thinking about brewing or buying kombucha, rather than just reading about it.
The practical read is straightforward. If a brewer or a curious drinker wants a kombucha with higher in-vitro antioxidant activity, the data here points to green or oolong as the base. If the priority is a specific aromatic profile, the choice is wider and more personal: each of the five teas in the study produced a distinct chemical and aromatic fingerprint, and the ranking on bioactivity does not translate directly into a ranking on flavor. Black, white, and pu-erh each have a real chemical identity in the finished cup, and drinkers who value those profiles are not choosing a lesser kombucha, they are choosing a different one.
What to watch next is the paper itself. The SciTechDaily summary provides the institutional framing, the lead quotes, and the headline comparative result, but the underlying Food Chemistry publication will carry the full quantitative detail: the specific compound-level differences across the five brews, the exact antioxidant assay methods, and the tea-to-tea ranking on each measured axis. The study's contribution is less "green tea wins" and more "the base tea is the lever," and the next step is seeing how the authors themselves present the magnitudes.
For now, the takeaway is the part that was hiding in plain sight on every kombucha label. The tea is not a flavoring. It is the substrate. The SCOBY reshapes it, but the leaf sets the terms.