Is kefir losing its fizz? The functional dairy identity crisis

Why kefir is losing its fizz: summary

• A taste test suggests only grain‑made kefir delivers traditional natural fizz
• Western kefir often lacks yeast due to manufacturing risks and preferences
• Products using cultures instead of grains could contain fewer diverse probiotics
• Brands prioritise smooth textures because some consumers dislike fizzy dairy drinks
• Kefir’s identity may fade without clear global definitions

Sat at a desk with three different brands of kefir lined up, today’s work involves a welcome mix of flavour exploration and reporting. Taste‑testing fermented dairy is not a typical 9‑5 task – and the gut health benefits are an added bonus.

The reason for the taste experiment? We’ve heard that kefir is losing its fizz – outside of Eastern Europe and Russia at least, where the traditional beverage is consumed daily. In these regions, kefir is naturally effervescent. So why doesn’t kefir in Western Europe, where its popularity is soaring, carry that same bubbly perception?

And with that, we find ourselves back at the desk with the taste test: an incredibly serious scientific experiment – the sort that involves no actual science but plenty of sipping – to determine whether kefir is truly losing its fizz outside of Eastern Europe, and what that might mean for its traditional identity.

Putting kefir to the taste test

First up is Danone’s Activia kefir – mango-flavoured, for fun. Bottle cap open, the creamy kefir pours easily into a glass. The beverage is thin enough for easy drinking, and slightly sweet in taste: it contains sugar, concentrated carrot juice, and mango purée after all.

Next up, Müller’s Biotiful Gut Health kefir – unflavoured. A much shorter ingredients list (milk and live kefir cultures) and while still smooth, it’s slightly thicker than Danone’s offering, championing the subtle sour notes associated with natural yoghurt.

In fact, in a blind tasting, both products tested so far could easily pass for yoghurt – the drinkable kind.

Then comes the Polish contender: Krasnystaw kefir. In the UK it appears in a few major supermarkets, though it’s far more commonly spotted in corner shops. A smaller, mainstream retailer is less likely to stock it.

Twist open the bottle and a faint fizz escapes. Pour it into a glass and a thicker, slightly clumpy texture emerges. And the flavour? Tangy, sour, and unmistakably effervescent. Properly tongue‑prickling fizzy. In a blind tasting, it could be mistaken for yoghurt that’s turned. But it is kefir – and it tastes as though it’s already doing the gut some good.

So three kefir brands, and three different taste and mouthfeel experiences. But just one carries that quintessential kefir effervescence. What’s going on? What makes some kefirs fizz, and others taste more like drinkable yoghurt?

What makes a functional dairy beverage ‘kefir’?

Let’s start with how kefir’s made. The traditional, functional beverage is centred around kefir “grains” – a combination of bacteria, yeast and other microorganisms that when added to dairy, kickstart the fermentation process.

Kefir’s slightly fizzy nature comes directly from this process, whereby yeasts in the kefir culture break down lactose into carbon dioxide.

So how does kefir differ from yoghurt? Both contain probiotics, but kefir made from traditional kefir grains contains significantly more – as many as 300 different species. According to personalised health start-up ZOE, which has a particular interest in gut health, not all kefir is created equal.

Some mass-produced products use bacteria and yeasts extracted from kefir grains, rather than the grains themselves. The result, according to ZOE, is a reduced number and lower diversity of probiotics in the kefir.

Drinkable yoghurt masquerading as kefir?

What kefir should and shouldn’t be is defined by the UN’s Codex Alimentarius. But the definition may not be perfect, according to professor Paul Cotter, who heads up Food Biosciences at Teagasc Food Research Centre in Ireland.

“Our experience shows that some kefir made from kefir grains do not perfectly match this. And also, this definition is not enforced universally.”

So what might a product claiming to be kefir, but which in fact is simply a fermented milk drink, look like? For Prof Cotter, a yoghurt product associated with streptococci and lactobacilli bacteria, which could be supplemented with other non-kefir derived strains, would fit the bill. But it would represent an “extreme example”, he says.

Some products devoid of traditional kefir microbes, but which carry the “kefir” label, do exist. But the market’s changing, according to the researcher: “Things have improved.”

And ultimately, Prof Cotter is happy to be a bit more lenient on what kefir is and isn’t, compared to the UN definition. “As long as the product is either made through a fermentative process that involves a kefir grain or contains a combination of strains that were originally isolated from a kefir grain, I don’t have a problem with it being called kefir.”

Why some kefir fizzes, while others remain flat

And so we’re back to that key question about kefir’s fizziness, or lack thereof. The taste test revealed that only the Polish-made kefir had the effervescence characteristic of traditional kefir, and looking at their ingredients lists, that was the only product in the line-up containing kefir grains. The other two contain kefir cultures instead.

Prof Cotter’s analysis of kefir made with grains reveals that the microbes present include different types of lactic acid bacteria, acetic acid bacteria, and importantly for the fizz, yeast. “Milk kefir made with kefir grains is more likely to contain yeast,” he confirms.

And yeast is one of the main contributors to fizziness. In many commercial kefir types, there is no living yeast. Why not? According to René Floris, chief innovation officer at food research organisation NIZO, it comes down to manufacturing convenience.

When yeast produces too much gas, it can risk “blowing up” the packaging, he explains. “That makes the original fizzy kefir a tricky product in common processing and storage lines.”

But that may not be the only reason yeast is avoided. “Original kefir is made with grains, and grains are much more difficult to handle in an industrial setting – therefore manufacturers typically don’t work with the classical kefir grains."

What consumers want, and don’t want, from kefir

But from a brand perspective, the lack of yeast in mainstream products is more closely tied to consumer insights. Kefir made by Biotiful Gut Health, recently acquired by dairy major Müller and which holds a 57% market share in the UK, doesn’t contain any yeast at all.

Although the company acknowledges traditionally fermented kefir does, since yeast is naturally present in all traditional kefir grains, it’s not convinced the “fizzy characteristics” associated with yeast best align with local tastes.

“Extensive consumer research in the UK shows that the majority of people prefer a smoother, milder and more consistent kefir taste and texture experience,” says Biotiful CMO Vince Lawson. “For that reason, we only use authentic kefir cultures. These are responsible for the recognised kefir taste and texture and the live cultures that deliver the core benefits of kefir.”

By focusing on these kefir bacteria, rather than on the yeast, the business says it’s able to deliver a product that’s “authentic in its microbiology”, but better aligned to what UK consumers actually enjoy. And that means, no “overly fizzy or lumpy texture” that yeast can create – and which came through loud and clear in the taste test of Poland’s Krasnystaw kefir.

Kefir: a traditional identity in crisis?

Traditionally fermented, prickly-tongue kefir, has not hit the mainstream in Western Europe. But kefir as a burgeoning category, absolutely has. Biotiful Gut Health is leading the charge, contributing 67% of total category growth, according to market analytics firm Circana.

Without a legally binding definition of kefir, the drink’s traditionally fizzy identity could fast fade. And that process may already be underway. Many consumers outside of Russia and Eastern Europe are still discovering kefir for the first time, explains Teagasc Food Research Centre’s prof Cotter. So whether kefir is losing its traditional identity in western markets or not may not be an immediate issue.

That’s not to say it couldn’t be in the future, however. It may become a problem in time, says the researcher, if fake kefir products become more commonplace on the market. “That said, I think many companies are conscious of the potential reputational damage, and so there is greater focus on having the correct species present.”

In the absence of a legally binding definition of what kefir is and isn’t, any traditional standard is challenging to enforce. But again, that may change in the coming years. Biotiful expects future standards to focus on ensuring products contain established live kefir cultures, rather than mandating the presence of yeast. In other words, greater focus on the beneficial gut bacteria, and less on the effervescent mouthfeel. “Any robust definition should include a meaningful measure of live bacterial count, generally at least two to ten billion live cultures per daily serving,” says CMO Lawson.

For now, consumers newly familiar with yeast‑free kefir are unlikely to lament its lack of fizz. If traditional tanginess is being dialled down, perhaps gut benefits are taking its place.

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