Interview: Dr. Thierry Tran, Dijon, France

Thierry Tran authored a 3-part series in SYMBIOSIS Magazine:

• Part 1: The Chemistry of Fermentation
• Part 2: The Five Senses
• Part 3: Evaluating Flavor Quality

(Back copies are available to order.)

He now offers independent consulting via Transverse Consulting, contact Thierry by messaging him on his LinkedIn profile. He has published over 20 research papers on topics such as ‘Identification of Key Parameters Inducing Microbial Modulation during Backslopped Kombucha Fermentation’ and ‘Polyphenols in kombucha: Metabolomic analysis of biotransformations during fermentation’ . This edited transcript of the podcast has been included since the audio quality of the phone interview was not as clear as hoped.

BOOCH NEWS: You’ve worked with kombucha for seven or eight years. You’re no longer a graduate student or postdoc. Are you working in a university, or what is your occupation?

THIERRY TRAN: I finished my postdoc about kombucha last September, and after that, I founded my own company, consulting about food science and specifically kombucha. I’m consulting for kombucha brewers, helping them set up new processes, and asking them questions about regulation, health claims, and anything related to kombucha products.

BN: When you say consulting, you focus on the biochemistry. You’re not consulting on marketing, sales, label design, or anything.

TT: Yes, absolutely. The process used to make a product is linked to its quality, and its quality is linked to every aspect of the product.

BN: No two kombucha companies are identical, right? They have their own fermentation process, source material, tea, sugar, and methods they might use. In the seven or eight years you’ve been working in this industry and focused on kombucha, what are some of the challenges, and what are some of the trends you’ve seen across commercial brands?

TT: In the last couple of years, it has been changing a lot. There are older and newer kombucha producers. The new companies learn from the older ones so that I see an evolution in the processes. In the beginning, there was a focus on the least complex, the simplest, and the most traditional processes possible—classical kombucha brewing like home brewing. Now I see that the kombucha brewers allow themselves to use more treatments such as pasteurization, filtration, and the addition of alternative sweeteners, as well as additional probiotics.

So, it has broadened the diversity of existing processes, and since kombucha is a new product, and there are no rules or regulations, anything can be done. Sometimes, this poses new challenges, so it’s a case-by-case situation where we have to work on very specific products that do not resemble another. So, it’s quite fascinating and quite complex at the same time.

BN: Yeah, you make an interesting point. You know I’m a home brewer. I’ve been doing it for 15 years or so in my basement. I have containers of two gallons each, and I ferment for a week, ten days. Maybe I put in some ginger or put it straight into the refrigerator; perhaps I want a little secondary fermentation, and I drink it. And for home brewers, there’s nothing else they need to do. There’s no reason for a home brewer to pasteurize, filter, or add other probiotics.

When you’re in the commercial market, however, some people will say you should never diverge from that. You should keep it authentic and do it exactly like a home brewer. But what are the trade-offs? Is it because people say they want a shelf-stable product that they need to pasteurize, or is it because they want to maintain consistency? What are some of the trade-offs you see? What are some of the things that drive those decisions by a commercial brewer?

TT: In the ideal world, we could transpose how we brew kombucha at home to an industrial setting. Unfortunately, it doesn’t work like that, as is the case for any food. Actually, because you’re expected to fulfill regulations, you have to have a product that is safe, and that is expected to be reproducible. That’s in conflict with the traditional process, which evolved as home brewing, and you don’t have the same expectancies. That conflicts with what both consumers and retailers expect.

So, in more detail, if you transpose your home brewing to an industrial setting, you have issues of flavor,  quality, and stability. A stable product may rely on the cold chain or not. And if not, then you must use pasteurization or filtration. And the question is, is it traditional when you do that? Is it still a traditional product?

And since there is no proper definition of what traditional kombucha is, since there is no regulatory framework to say it is or is not, it’s up to the brewers to decide if they agree with this practice and if they choose to use it. Because if not, they might not sell their product as easily as they want because the market and the food chain is as it is. And it’s also the same question with probiotics. If we [add] probiotics, is it still traditional kombucha?

But if you don’t use probiotics, you’re not, in Europe, allowed to have claims of probiotics on your label. So, it’s a matter of representation and decisions from the brewers, at least before [new] regulations are applied.

BN: Wow. Well, there’s a lot to unpack there. One thing to clarify is adding probiotics. Specifically, are there regulations that if you don’t add probiotics like bacillus coagulants, I think it’s called, or “live cultures” after secondary fermentation, you won’t able to say on the label that it contains probiotics? Is that correct?

TT: Yeah, absolutely. You have different options. There are lots of probiotics that exist —  yeast or bacteria — but those are specific strains that are recognized by the regulations. For example, in the European Union, you have a list of bacterial and fungal strains recognized as probiotics. And suppose you don’t add them to the product in sufficient population of live microorganisms. In that case, it cannot be recognized as probiotics because, for now, the microorganisms used for kombucha fermentation have not been proven individually to bring health benefits. They are not considered probiotics, so no health claims can be applied to those products.

BN: I see. It’s something that, again, the home brewer wouldn’t do, but they’re not trying to meet any labeling requirements. You concluded your series in SYMBIOSIS talking about techniques for elevating the flavor quality of kombucha.

When a commercial kombucha is processed, and they make the trade-offs, if you like, or they think about achieving stability, where do flavor and taste come into that? If they say sugar-free, but that means they’ve added stevia, or they say shelf-stable, so they’ve pasteurized or filtered. Do you see the challenges for commercial kombucha brewers in becoming distinctive and consistent in terms of flavor and taste? How does that play in terms of the chemistry?

TT: So, for stability, there is the question of, do I rely on the cold chain? Is that sufficient for me to ensure that the quality, the sensory quality, and the chemical and microbiological quality will be sustained during the product’s shelf life? There are decisions to be made. If you decide to apply physical treatment, such as filtration or pasteurization, for example, it will impact the product’s flavor. When I say flavor, it also encompasses the visual aspect because when you filter, you will change the beverage’s turbidity or cloudiness.

And so, this has to be anticipated, which means that, okay, you are working hard to perfect your flavoring and select the right ingredients. Still, you must also test how it will evolve with the shelf life and how it will react to any treatment you intend to apply. So that must be considered. Sometimes, there is a compromise between what you’re seeking in terms of flavor and what you must do for your product to stay stable over time.

Some compromises would be satisfactory for the consumer. I want to add that, as producers, you have a certain idea of how your product would taste. But in the end, it’s also the consumers who will buy it, and it’s a good idea to ask the consumers, for example, by sensory testing, what they prefer. It must be both. It doesn’t have to be just the producers or the consumers, but a place in between that will satisfy both of them.

BN: Yeah, that’s great. Well, this has been a very interesting conversation. One final question from your perspective—having been involved in a very, very detailed scientific basis in this industry—where do you think this market will be in the future?

TT: Okay, so we know that there are market projections until 2029, and they plan for the market to almost double, I think. It’s a very dynamic market worldwide. I think there will be regional discrepancies. In France, I’m not sure this product will penetrate the market as well as in other countries. Many things will rely on marketing, but also on science because I know that there is a lot of research at the moment about the health benefits of fermented food.

In fermented food, you have microorganisms. They can be live, they can be dead, and they transform the food. So, new metabolites with potential good or bad effects change the composition that might bring something for human health. And we might have discoveries that change how we consider fermented food in general, including kombucha. Depending on those discoveries, depending on this research, maybe we can expect new things from those fermented foods in terms of health benefits, but not as individual products that will solve all your health issues, but rather as public recommendations.

That’s something that I feel inspired by—that governments would recommend consuming fermented food in general, without focusing on kombucha specifically, to bring health benefits to the whole population. I think this kind of perspective can really boost the consumption of kombucha, but it will also boost other foods, and that’s why I don’t want to dislocate kombucha, the trends of kombucha, from the trends of other fermented foods. I think we can really expect a lot from science and research in the future, and that would be, in my opinion, if it happened, the biggest shift in the consumption and market for kombucha.

BN: Well, I think that would be an amazing change, and I congratulate you on your years of research and being one of the world’s experts on kombucha. It’s been great talking with you. Good luck with your consulting, as you now offer your services to people. I’ll put the link to your company on the website, and it’s good luck and bonne chance.

TT: Thank you very much. Have a good day.

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