How to Make Kefir at Home

Kefir is one of the most probiotic-dense foods you can eat. The commercially made kefir available in supermarkets contains a decent number of live cultures, but if you want the real thing — dozens of bacterial and yeast strains in significant quantities — making it at home from live kefir grains is a different order of product entirely.

What kefir grains are

Despite the name, kefir grains have nothing to do with cereal. They are small, gelatinous clusters of bacteria and yeast held together in a protein and lipid matrix. They look roughly like small cauliflower florets or soft cottage cheese curds.

The grain is a living culture. When you add it to milk, the bacteria and yeast ferment the lactose, producing lactic acid, small amounts of alcohol, and carbon dioxide, along with a complex range of probiotic organisms. The grain itself remains intact, grows slightly with each batch, and can be reused indefinitely.

A well-maintained kefir grain contains between 30 and 50 different species of bacteria and yeast in a stable symbiotic relationship — significantly more microbial diversity than commercially produced kefir or most probiotic supplements.

Milk kefir versus water kefir

There are two distinct types of kefir grain and they are not interchangeable.

Milk kefir grains are the traditional form, used with cow’s milk, goat’s milk, or other dairy milks. The resulting kefir is slightly tangy, pourable, and mildly effervescent. It contains a broad range of Lactobacillus and Lactococcus species alongside various yeasts and is the more microbiologically complex of the two.

Water kefir grains (also called tibicos) are a different culture that ferments sugar water, fruit juice, or coconut water rather than milk. The resulting drink is lighter, naturally fizzy, and completely dairy-free. Water kefir generally contains fewer bacterial strains than milk kefir but is a good dairy-free option for anyone looking to increase probiotic variety in their diet.

The two are different cultures and cannot be substituted for each other.

Lactose intolerance and kefir

Many people who are lactose intolerant can drink milk kefir without problems. The fermentation process breaks down most of the lactose — the bacteria consume it as their food source during fermentation. A properly fermented 24-hour kefir typically contains very little residual lactose. Most people with lactose sensitivity find they tolerate it well, though individual responses vary.

Making kefir at home

The process is straightforward:

1. Add kefir grains (roughly a tablespoon) to a jar of milk (around 500ml)
2. Cover loosely — not airtight, as fermentation produces CO₂
3. Leave at room temperature for 24–48 hours
4. Strain out the grains and refrigerate the finished kefir
5. Add the grains to fresh milk and repeat

The longer you ferment, the thicker and more sour the result. Most people find 24 hours at around 20°C produces a mild, slightly tangy kefir. Warmer temperatures speed up fermentation noticeably.

The grains grow over time. Once you have more than you need, you can share them, eat the excess (they are edible and nutritious), or freeze a portion as a backup culture. A well-kept culture will last for years.

Why home-made kefir is worth it

Commercial kefir is a decent product, but the pasteurisation and short ferment times used at scale limit both the strain diversity and the colony counts compared to a properly fermented home batch. For anyone serious about gut health and probiotic diversity, making your own gives you a product that no shop-bought version matches on paper.

Where to find kefir grains in Cardiff

We stock kefir grains at Beanfreaks, along with ready-made kefir if you want to try it before committing to making your own. Ask in store for current availability.

• Roath: 95 Albany Road, CF24 3LP
• Canton: 124 Cowbridge Road East, CF11 9DX
• Royal Arcade: 8 Royal Arcade, Morgan Quarter, CF10 1AE

Get in touch to check stock before visiting.