Milk kefir is a fermented milk drink made with live grains that you strain out and reuse after every batch. Count 20 to 30 g of grains per litre, 18 to 30 hours at room temperature, about 55 kcal and 3 g of protein per 100 ml. Part of the lactose is broken down during fermentation. The culture never needs replacing because it grows. Traces of alcohol form during fermentation, usually under 0.5 per cent.
Milk kefir sits between yoghurt and buttermilk, and most descriptions of it stop at that comparison. This page goes further: what is in the glass, what the fermentation time changes, what it replaces in the kitchen, and what nobody should claim about it.
The line that matters is the culture. Yoghurt is made by adding selected strains to milk, and you can transfer a spoonful once or twice before it fades. Milk kefir is made with a solid cluster of bacteria and yeasts held in a matrix the culture builds itself. You lift it out, put it in fresh milk, and it works again. That is why kefir travelled from household to household while yoghurt cultures stayed industrial.
Water kefir grains and milk kefir grains are two different cultures. Translucent water grains do not survive in milk, and white milk clusters do not work in sugar water. Check the wording before buying.
| Per 100 ml | Milk kefir | Plain yoghurt | Whole milk |
|---|---|---|---|
| Energy | about 55 kcal | about 60 kcal | about 65 kcal |
| Protein | about 3 g | about 4 g | about 3 g |
| Calcium | from the milk | from the milk | from the milk |
| Fibre | 0 g | 0 g | 0 g |
| Lactose | partly broken down | partly broken down | fully present |
| Live cultures | yes, composition varies | yes, defined strains | none |
| Alcohol traces | under 0.5 per cent | none | none |
Two rows deserve attention. Fibre is zero, as it is in every fermented drink, so milk kefir cannot replace vegetables, pulses or wholegrains in that respect. And the composition of the live cultures varies from batch to batch, which is exactly why no one can put a number on it.
| Room temperature | Mild | Balanced | Sharp |
|---|---|---|---|
| 18 C | 24 hours | 30 hours | 36 hours |
| 22 C | 14 hours | 20 hours | 26 hours |
| 24 C | 12 hours | 18 hours | 24 hours |
| 28 C | 10 hours | 14 hours | 18 hours |
This is why two people following the same instructions get different results. A recipe that says twenty four hours without naming a temperature cannot be right in January and in July. Judge milk kefir by taste, and use the table to know roughly when to start tasting.
| Instead of | Ratio | Result |
|---|---|---|
| Buttermilk in batter | 1 to 1 | same texture, slightly tangier |
| Yoghurt in dressing | 1 to 1 | thinner, needs a little more oil |
| Milk in a smoothie | 1 to 1 | thicker, more sour |
| Sour cream in a sauce | 1 to 1, off the heat | lighter, less fat |
| Milk on cereal | 1 to 1 | thicker, more filling |
| Cream cheese | 1 litre gives about 250 g | drain 12 to 24 hours |
Never heat milk kefir above about 40 C. It splits into curds and whey and the live cultures die. Take the pan off the heat, let it cool for a minute, then stir it in.
Five minutes of work per batch. Milk kefir asks for nothing else, and the grains cost nothing after the first purchase because they multiply.
Milk kefir grains are neither a plant nor a fungus, despite some of the older names. They are small, irregular white clusters, a little like miniature cauliflower florets, made of a protein and polysaccharide matrix that the culture builds itself. Inside that matrix live several groups of microorganisms working together.
| Group | What it does | What you notice |
|---|---|---|
| Lactic acid bacteria | turn lactose into acid | the sour taste, the thickening |
| Yeasts | produce gas, aromas and traces of alcohol | the slight fizz, the yeasty note |
| Acetic acid bacteria | work at the surface | a faint vinegary edge on long batches |
Because it is a community rather than a single strain, the balance shifts with its surroundings. A warm summer favours the yeasts, a cool room favours the acid producers. That is why the same milk kefir tastes different in July and in January without anyone having done anything wrong.
The milk changes the result more than any other choice. The culture works in all of these, but the texture and the flavour move considerably.
| Milk | Texture | Flavour | Time at 22 C |
|---|---|---|---|
| Whole cow milk, pasteurised | thick, creamy | mildly sour | 18 to 24 hours |
| Semi skimmed cow milk | medium | sour, less body | 18 to 24 hours |
| Skimmed cow milk | thin | sharp | 18 to 24 hours |
| Ultra heat treated milk | thin | flat | 20 to 26 hours |
| Goat milk | medium | strong, distinctive | 16 to 22 hours |
| Sheep milk | very thick | full, slightly sweet | 16 to 20 hours |
| Raw milk | variable | complex | 14 to 20 hours |
Plant milks do not work as a permanent home for the grains. A single batch in oat or coconut milk is possible, but the culture has no lactose to live on and weakens over successive batches. Return the grains to dairy milk to recover them.
This is the part that decides whether a culture survives in a real kitchen. Milk kefir asks for one short handling every day or two, and nothing else.
| How often | What to do | Time |
|---|---|---|
| Every 1 to 2 days | strain, rinse the jar, add fresh milk | 5 minutes |
| Weekly | check the grains, remove the surplus | 2 minutes |
| Before a trip | grains in milk in the fridge | 3 minutes |
| After a trip | one batch to wake them up | 1 fermentation |
| Never | buy the culture again | not applicable |
The last row is the real difference from a shop bought drink. Well fed grains grow and divide, so after four to six weeks you usually have twice as many as you began with, and the surplus can be passed on.
Sooner or later there are more grains than one litre needs. There are three sensible uses and only one bad one, which is throwing them away.
That is the economics of milk kefir in one paragraph: the culture is worth more at the end of the year than at the beginning, because there is more of it.
A jar that stood a day too long has separated into a firm white layer and a yellowish liquid. Nothing is lost, it is simply no longer a drink.
| Use | How | Yield per litre |
|---|---|---|
| Fresh cheese | drain in a cloth 12 to 24 hours | about 250 g plus whey |
| Herb dip | drain 2 hours, add salt and chives | about 400 g |
| Baking liquid | use the whey in bread dough | about 700 ml of whey |
| Marinade | 2 to 4 hours for poultry | enough for about 1 kg |
Authorised health claims in the European Union are listed by the European Food Safety Authority. If a claim is not in that register, nobody may make it, ourselves included.
Live milk kefir grains
Shipped hydrated and active, ready for a first batch the day they arrive.
See the grainsThe step by step method: how to make kefir. The comparison with the water version: water kefir and milk kefir.
A fermented milk drink made with live kefir grains, small white clusters that are strained out after each batch and used again. It ferments at room temperature for 18 to 30 hours and ends up pourable and mildly sour, somewhere between yoghurt and buttermilk.
The culture. Yoghurt uses selected strains added to each batch, while milk kefir uses a solid, reusable culture. Yoghurt also needs warmth and sets thick, whereas kefir ferments at room temperature and stays pourable.
18 to 30 hours at room temperature. At 18 C count 30 to 36 hours, at 28 C only 14 to 18. Taste rather than watch the clock: pleasantly sour means it is ready.
Some. Part of it is broken down during fermentation, and how much depends on time and temperature. A longer fermentation lowers it further but makes the drink sharper. Tolerance is individual and can only be tested.
Fresh pasteurised whole milk gives the best texture. Ultra heat treated milk works but produces a thinner result. Goat and sheep milk both work and taste stronger.
Yes, as long as they are fed regularly. They grow and divide, so after a few weeks you will have more than you started with. That is the difference from a sachet of freeze dried ferments, which lasts one to three transfers.
It fermented longer than you wanted. Stir it back together, or drain it through a cloth for 12 to 24 hours and you have about 250 g of fresh cheese per litre.
Yes, but never above about 40 C. Add it off the heat, at the end. Heated, it splits into curds and whey and the live cultures die.
