How to make milk kefir: the basic method

What you need

Milk kefir is about the simplest thing you can ferment in a kitchen. There is nothing to heat, nothing to sweeten and only one thing to weigh: the grains. For one litre:

• 20 g of live milk kefir grains. With 10 g you make half a litre a day.
• 1 litre of whole milk. Ordinary pasteurised whole milk from the fridge (the blue top) is perfect. What the other milks do is explained in Which milk for kefir?

For equipment: a glass jar of a little over a litre with a wide mouth (a large jam jar or a clip-top jar with the lid left open), a plastic or stainless steel sieve, a wooden or plastic spoon, a tea towel with an elastic band, and a bottle or jar with a lid for the finished kefir. You probably have all of it in the kitchen cupboard already.

Step by step

How do you know it is ready?

• The milk has set. Tilt the jar and the kefir moves as one mass, like a runny yoghurt, and pulls away from the glass.
• It smells fresh and sour, with a light note of yeast or bread dough.
• A few drops of clear whey appear down the side of the glass or at the bottom. That means ready, or nearly. A thick layer of whey means it has gone well past the point.
• The taste is gently sour and creamy, sometimes with a faint prickle on the tongue.

The first batches after the grains arrive are often thinner. The grains are getting used to your milk and your kitchen. After three or four batches the kefir is usually smooth and even. If it is still thin after a week, have a look at Milk kefir too thin or too thick?

Getting the flavour you like

Milk kefir is alive, and it changes with the seasons. A few simple adjustments steer it where you want it. Change one thing per batch, so you know what made the difference.

A second fermentation for milk kefir

Just as with water kefir, you can let milk kefir carry on working after straining, this time without the grains. Pour it into a bottle with a lid and leave it on the worktop for half a day before it goes into the fridge. It turns milder and fuller, and sometimes picks up a light sparkle.

You can add something to the bottle as well: a strip of orange or lemon zest, a cinnamon stick or half a vanilla pod. Fresh fruit is better added just before drinking, because it makes the kefir separate sooner.

Quantities and ratios

The grains grow with every batch. After a few weeks you will have more of them, and your kefir will thicken and sour faster. That is the moment to take some grains out or use more milk: keep to roughly 20 g per litre. What to do with the extra is covered in Caring for milk kefir grains.

Finding your rhythm

Plenty of people strain their kefir in the evening, after the dishes. That way there is cold, fresh kefir waiting in the morning for the porridge, a bowl of muesli or a glass on its own. If you prefer to set it in the morning, it will be ready the next morning, or by the afternoon in a warm spell, for a smoothie or a dressing.

Two jars used in turn makes life easier. You do not have to wash the jar after every batch either: a thin film of kefir on the glass does no harm. Wash it once or twice a week in hot water and rinse it well so no washing-up liquid is left behind.

British kitchens are not known for being warm. In winter, in a kitchen that drops to 16 or 17°C overnight, a batch can need 30 hours. A shelf in or near the airing cupboard, or a spot near (not on) a radiator, will bring it back to 24. In a warm July week it can be ready after 18 hours. Go by the kefir, not only by the clock.

Common mistakes

• Too many grains for too little milk. The kefir quickly splits into curds and whey. Keep to 20 g per litre.
• Rinsing the grains under the tap. Not needed, and it slows them down. Straight into fresh milk is all they want.
• A jar on a sunny windowsill. Too warm: the kefir turns sour and separates.
• Pressing hard in the sieve. Stir gently, do not push.
• Too long without fresh milk. On the worktop the grains want new milk every day.
• Plant drinks as an everyday base. The grains live on animal milk. More on that in Kefir with plant milk.

If something looks different from what you expected, the answer for each situation is in Milk kefir problems.

What to do with your kefir

Cold from the fridge, in a glass, it is already good. But the real surprise is how well it fits a British kitchen. Anywhere you would use buttermilk, natural yoghurt or soured cream, kefir works.

• In scones, pancakes and drop scones, in exactly the same quantity as the buttermilk. It is sour and thick, so it reacts with the bicarbonate the same way. The comparison is in Kefir or buttermilk?
• Stirred through oats the night before: kefir overnight oats, or simply poured over a bowl of hot porridge.
• Strained overnight in a cloth for strained kefir cheese, lovely on wholemeal toast or a warm crumpet.
• Blended with a ripe banana: the banana kefir smoothie.
• In pancake batter on Pancake Day, or in an apple cake made with Bramleys.

How long does homemade kefir keep?

In a closed bottle in the fridge, fresh milk kefir stays good for several days. It slowly gets sharper, because the fermentation never stops completely in the cold. It is at its best in the first few days, and a bottle that has turned too sour to drink is still perfect for baking. More on that in How long does kefir keep?

Frequently asked questions

No grains yet? Our live milk kefir grains come from traditional methods: unique and vigorous. They come in 10 g or 20 g, from £14. Standard tracked delivery is free from £35 anywhere in the UK, and all prices include VAT. Everything else about milk kefir is in the complete milk kefir guide.