October 13, 2022

Fermentation: The Power of Transformation

An interview with the scientists behind our new yogurt alternatives.

Fermentation has a long-standing tradition of preserving and transforming food. Baking sourdough bread, brewing kombucha, making kimchi, or pickling vegetables – fermentation is everywhere. But what exactly happens during this process? And what distinguishes plant-based from dairy fermentation? Let’s talk about the power of fermentation with the two people at vly who know it best: the microbiologist and food technologist behind our fermented yogurt alternatives, Anna and Gaba.

Gabriela Biel, M.Sc. (left) & Anna Birke, Ph.D. (right) in our vly lab in Berlin.

Hi Anna & Gaba, you are the two people responsible for our new and first-ever fermented products. Let’s start with your personal favourite fermented food. What is it?

Anna: I especially like fermented beverages, like water kefir and pasteurized kombucha. Kombucha is produced by fermenting sugar-containing tea, whereas water kefir is the result of fermenting sugar and water, to which fruits can be added.

Gaba: For me, it’s sourdough bread and raspberry kombucha. Normal bread is made with baker’s yeasts, while sourdough bread requires a starter composed of lactic acid bacteria and wild yeasts. So the starter is used to ferment the bread dough before baking. The final effect is that it’s slightly sourer and more flavourful.

You both work in the lab at vly. One of you in product development and the other in the research and innovation team. What are your tasks there?

Gaba: I’m a product developer, which means I formulate and test hundreds of prototypes to design the best-tasting product that consumers will love. Since I have a microbiology background and enjoy fermenting food at home, I took responsibility for the yogurt alternative project.

Anna: I’m a microbiologist working as a fermentation scientist. My first project when I joined vly was screening different vegan starter cultures and adapting the base recipe to maximize fermentation efficiency. When Gaba took over the development of the yogurt alternatives, I transitioned from product development into carrying out and coordinating research projects that are driving innovation at vly in the field of fermentation and microbiology.

💡 What are starter cultures? Starter cultures are microbial communities, which are usually bacteria and/or yeasts. In food applications, they are added to a recipe to direct the fermentation. The base ingredients might already contain some microbes, but by adding large numbers of the “right” microbes, there is some level of control over the biochemical reactions that happen during the fermentation.

To better understand what you did, can you explain to us exactly what fermentation is?

Anna: Simply put, fermentation describes a process that uses either cells, such as microorganisms, or enzymes, the “working force” of a cell, to convert compound A (for example sugar) into compound B (like lactic acid).

Yogurt is a great product to illustrate how this works. We start out with milk and harness the power of fermentation to transform it into yogurt. Could you please elaborate what happens during the process on a smaller scale?

Anna: Sure. For our yogurt alternatives, we used so-called lactic acid bacteria, which are microorganisms commonly used in food fermentation. They convert simple sugars into organic acids, such as lactic acid. Not only does this make the yogurt alternative taste acidic and fresh, but it also causes a drop in pH, resulting in the creamy texture characteristic of yogurts. That’s because the pea protein forms a gel network. Since the bacteria metabolise, i.e. “eat” the sugar, our yogurt alternative ends up being almost entirely sugar-free. The low pH of the yogurt alternative combined with other substances produced by these useful lactic acid bacteria ensures that the yogurt alternative is shelf-stable for a long period of time.

Since the bacteria metabolise, i.e. “eat” the sugar, our yogurt alternative ends up being almost entirely sugar-free. 

You spent two years in the lab, researching and spending a lot of time on fermentation and testing various prototypes. The fact that the development was so labor-intensive also has something to do with the state of research. In the field of milk and dairy products, research has been going on for decades. Not yet in the work with plant proteins. What is the main difference between a plant fermentation process and a milk fermentation process?

Anna: The two biggest differences between a plant-based yogurt alternative fermentation and a traditional dairy milk fermentation are in the base we use. For dairy yogurts, it’s dairy milk and for our yogurt alternatives, we used a base containing plant protein, sugar, and plant oil. The main source of carbohydrates in dairy milk is lactose. In our pea protein-based milk alternative, sucrose is the sugar available to the bacteria. Moreover, the proteins found in dairy milk, namely primarily casein and whey, are structurally very different from the various types of proteins found in peas. Since proteins are super important for the bacteria to work their magic during fermentation, optimizing the fermentation conditions for them to be “happy” with the plant proteins took some time.

Since proteins are super important for the bacteria to work their magic during fermentation, optimizing the fermentation conditions for them to be “happy” with the plant proteins took some time.

Gaba: To add to that, plant-based starter cultures are still not fully adapted to a wide range of different plant protein types, so the fermentation time is usually longer for yogurt alternatives (up to 16 h) compared to dairy yogurt (6-8 h). Overall, the fermentation of yogurt alternatives is a bit less efficient in acidification compared to dairy yogurt. We had to run a lot of trials and tweak our ingredients to make the fermentation work as efficiently as possible. I believe we nailed that.

What would you say was the biggest challenge in fermentation?

Gaba: The biggest challenge was getting the starter cultures to grow and to use the nutrients from our base. In addition, different starter cultures give different taste results. So another big challenge was to select a starter that would produce the most pleasant flavour compounds while at the same time efficiently lowering the pH.

Anna: In addition to what Gaba said: The texture was an issue at one point because we were using a very neutral pea protein source that had been extracted in a way that it wouldn’t form a gel network any longer. Most yogurt alternatives on the market include stabilizers, such as pectins and starches. But we were convinced we could do without those additives. We cracked it in the end, but it was certainly a challenge.

And the results taste amazing. So with the help of fermentation, you can change the taste, texture, and also the shelf life of food. This definitely has an impact on the plant-based food industry. What do you think, what role can fermentation play in the future?

Gaba: Fermentation is already gaining a lot of interest in the area of plant-based food development. That’s because of its numerous benefits - it can improve taste, texture, digestibility, and nutritional composition. What is already happening now and will be even bigger in the future is precision fermentation. It uses microorganisms to produce target compounds such as vitamins, which can be then purified and used to enrich products.

That’s because of its numerous benefits - it can improve taste, texture, digestibility, and nutritional composition.

Anna: Personally, I’m convinced that fermentation is the key technique to food security in the future. And I’m not just talking about making kimchi, I’m talking about biotechnology fermentation, like the precision fermentation technology Gaba mentioned. It will allow us to make our food system as circular as possible, hopefully, move away from unsustainable feedstocks, and help us create more tasty plant-based products that are nutrient-dense, healthy, and accessible to as many people as possible. It will also help us make the transition from a primarily animal-based food system to a primarily plant-based one. This transition is crucial for securing our future on this planet for at least two reasons: climate change and global health. I’m sure most people are aware of the issue of global warming and climate change and how it’s threatening our ability to feed the human population. I think fewer people are aware that animal husbandry also affects global health in two other ways. The first one is zoonotic diseases, diseases caused by pathogens transmitted from animals to humans. But put simply, as long as we continue to farm and eat animals, we’re going to get their diseases. The second one is the emergence and spread of antimicrobial resistance (AMR for short), which is an ongoing and increasing global health threat. I've put together a few related links for those who want to read more about it.

It will allow us to make our food system as circular as possible, hopefully, move away from unsustainable feedstocks, and help us create more tasty plant-based products that are nutrient-dense, healthy, and accessible to as many people as possible

Thank you for your time and insights into your work. And finally, one last question: Which of our yogurt alternatives is your favourite, and how do you like to eat it?

Anna: The strawberry one. I eat it plain.

Gaba: Mango! I eat it with homemade granola and berries. It is just perfectly sour and super refreshing, which is great during hot summer days. And in winter, it brings you back to the memories of holidays. So it is perfect for every occasion.

If you want to learn more about how our food habits impact climate change and global health, Anna has put together some references and literature for you:

Written by Helena Brune