Experiments in Kefir

What is kefir?

I’ve been making kefir at home for around 18 months now and have become very fond of this lusciously thick yet refreshingly fizzy drink. I use traditional kefir grains and add them to whole organic milk. Fermentation typically happens between 24 and 36 hours, depending on ambient room temperature.

But let’s back up; what exactly is kefir? Well, essentially it’s two things: it’s a both a cultured milk drink with a uniquely fizzy, tangy taste, and it’s also the peculiar ‘grains’ that cause milk to ferment and transform into this drink. Actually, these days it’s a third thing as well: a laboratory-inoculated starter culture that also turns milk into a richly textured, slightly fizzy drink.

Kefir is said to have originated thousands of years ago in the Caucasus – the mountainous region between Europe and Asia that spans borders with Russia, Georgia, Azerbijan and Armenia. According to Wikipedia, kefir grains themselves are ‘a combination of lactic acid bacteria and yeasts in a matrix of proteins, lipids, and sugars.’

The actual grains look like creamy overcooked cauliflower (see below): gelatinous clusters of lactic acid bacteria and yeasts. Essentially, the grains are part of the strange world of SCOBYs (Symbiotic Cultures Of Bacteria and Yeasts), which includes apple cider vinegar ‘mothers’, kombucha ‘mushrooms’ and sourdough bread starter.

While this is the only kefir I’ve known, I was recently talking to Tom Calver of Westcombe Dairy and he suggested I try some of the Hansen eXact KEFIR 1 culture they sell. Intrigued, I said I’d set up a test where I’d make a number of batches of kefir, using both grains and culture, as well as different milks, to see what variations I could observe. I also wanted to know how cultured kefir compares to grain kefir, both in terms of production and the finished product.


Generally, I make my ‘everyday’ grain kefir with Co-Op’s Organic Whole Milk, which I find gives a balanced flavour and a medium-thick texture that stays stable in the fridge once strained. I make kefir in one litre batches, using around 50 grams of grains. With this method, I find full fermentation usually happens within 24-36 hours. Other milks I tend to use are Bruton Dairy’s Whole Milk, Yeo Valley Whole Milk and Sainsbury’s ‘SO’ Whole Milk.

For the following experiments I was also lucky enough to get a few litres of Westcombe Dairy’s raw milk, the same milk they use to make their excellent cheeses, so I used this to make both a batch of grain and cultured kefir.


Making cultured kefir is a much easier process than the one detailed above. Most significantly, there are no grains, just a powdered blend of cultures that simply needs dissolving into the milk. Therefore, you don’t need to strain cultured kefir once it’s fermented like you do with grain kefir (to retrieve the grains for future makes).

Now that I’ve experimented with both, I see the difference between cultured kefir and grain kefir in much the same way I think of bakers’ yeast bread and sourdough bread. One’s not necessarily better, but generally the wild/natural one is more complex and less easily controlled. Either way, I believe that if you use good ingredients and focus on the outcomes, you can make excellent kefir using either method.


For the first batch of cultured kefir I kept to Hansen’s make guidelines. I used Westcombe’s raw milk (a day after milking), bringing one litre to the boil, holding it at a simmer for four minutes, then letting it cool. At around 35°C I added two grams of Hansen’s eXact Kefir culture, whisking slowly until fully dissolved. I left the kefir at ambient room temperature for 26 hours (although the milk set very fast, within a matter of hours). The finished kefir was very thick, almost puddingy, with a lusciously smooth texture (see below). The flavour was clean, yeasty and faintly lemony, with a medium CO2 level.

For this make I wanted to stick to my ‘typical’ grain kefir method, but using culture instead. I whisked 2g of Hansen eXact Kefir culture into 1 litre milk, leaving this in a dark place at room temperature for 25 hours. After this time the milk had thickened up well, while retaining a ‘natural’ kefir-like consistency (i.e. it wasn’t as uniformly smooth as experiment 1). The flavour was sweet and quite authentic, albeit with a slightly confected lemony flavour. There was good CO2 and a fairly pronounced yeasty backnote.

This make was very similar to the one above. I inoculated 1 litre of Westcombe raw milk with 2g of culture (whisked in for around three minutes) and left it at ambient room temperature for 26 hours. By this point it achieved a firm, semi-set thickness with good CO2 and a very good flavour, combining the distinct lactic flavour of the milk with the sweet, yeasty profile of the culture. Interestingly, the texture had a light graininess to it, not too dissimilar from natural grain kefir (see below).

Having made my ‘everyday’ kefir with various homogenised and unhomogenised milks (to varying levels of success), I was intrigued to be able to try Westcombe’s Dairy’s super fresh raw milk. This might be a bit ‘hippie’, but I genuinely believe that the properties inherent in a milk are just as key to the finished kefir as the properties the grain adds, such as their wide array of probiotic bacteria and yeasts.

I followed my standard method for this make (1 litre of milk to 50g grains). After 24 hours the milk had separated well with a nice yellow whey around the grains (see video below). Once strained, the kefir had a rich consistency and a good structure. The flavour was sweet and lactic, with no bitterness and a definite ‘Westcombe’ note (if you know their cheeses, you’ll know what I mean!). This was a really fine kefir, both in terms of texture and flavour.


The above experiments were really helpful in expanding my knowledge of kefir and helping me understand more about the variables that can affect the finished product. I still hold my ‘everyday’ grain kefir (with Co-Op’s organic whole milk) in high regard, but using that as the standard, here are some notes:

The make with cultured kefir with the ‘cooked’ Westcombe milk (experiment 1) really impressed me. Although the finished kefir was far removed from my everyday grain kefir, as a ‘cultured milk product’ in its own right I thought it was lovely. The texture was lusciously thick and smooth, and I liked the sweet, faintly yeasty, easy-going flavour. I could see how a first-time kefir drinker would much prefer this over a more tangy, less smooth grain kefir.

The make with grains and Westcombe raw milk (experiment 4) also impressed (and surprised) me. The results were very different from using Bruton milk (whose dairy is just down the road from Westcombe’s) and I really liked the rich, complex flavour and thick texture it produced. It’s just a shame this milk isn’t available commercially otherwise I’d use it all the time.

And I was very happy with the other two cultured kefir makes as well. It was interesting how the Hansen culture behaved under different conditions. The way the finished kefirs had more of an authentic, sightly grainy texture made me realise that not all cultured kefirs have to conform to a prescribed style. I was particularly impressed with the cultured Westcombe raw milk make (experiment 3), which had a very authentic texture and a flavour that married both the inherent qualities of the milk with the profile of the culture.

I look forward to further explorations with this fascinating cultured milk. Watch this space!

William Thomas – Bristol-based food writer and kefir enthusiast.