How to stop kefir fermentation and put the grains on pause?

By Nik, founder of 東歐嚴選｜kefir.link and former chef · First published 4 May 2024 · Updated 4 November 2026

A trip is coming up, or a week so full that you have no time to strain kefir. Your grains can simply take a rest. In a closed jar of fresh milk in the fridge, they slow right down and wait for you for up to a month. Here is how to put them to rest, how to look after them while they wait, and how to wake them up again.

The short answer

• To pause: cover the grains with fresh milk in a clean glass jar, close the lid and put the jar in the fridge.
• How long: change the milk about every 7 days. The grains can rest like this for up to a month.
• Where: at the back of a fridge shelf, where the cold stays steady.
• Coming back: pour the resting milk away and use less milk for the first batches. The first batch or two will be slower.
• Away for longer: take the grains with you, or leave them with a friend who makes kefir.

Ask us on LINERead the kefir-making guide

How we checked this guide

• Our printed care guide: the pause method comes from the guide that comes with our grains.
• Our LINE answers: what we tell customers who travel or take a break, from years of their questions.
• Food-safety guidance: the kefir guide of the British Columbia Centre for Disease Control, and Taiwan FDA advice on fridge temperature. Each is linked next to the sentence it supports.

Before you go: put the grains to rest

It takes about five minutes, right after you strain your last batch.

1. Strain your last batch. Drink the kefir, or keep it in the fridge in a closed bottle. Sealed, it keeps for up to 21 days.
2. Take a clean glass jar that is completely dry. Choose one big enough to hold plenty of milk.
3. Add the grains and cover them with fresh milk. Use fresh whole milk, the same milk you ferment with. The grains should sit well under the milk.
4. Close the lid. In the fridge a closed lid is right. Kitchen paper with a rubber band is for fermenting at room temperature.
5. Put the jar at the back of a fridge shelf. The door warms up every time it opens, while the back of a shelf stays steady (TVBS Health). Keep the fridge at 7°C or below (Taiwan FDA via CNA).
6. Write the date on the jar. Then you always know when the milk is due for a change.

How long can the grains rest?

The cold slows down the lactic acid bacteria and yeasts in the grains. They still feed slowly, so the milk turns sour and separates over time. Fresh milk every week keeps them fed.

Food-safety guidance says the same: grains kept in fresh milk in the fridge stay at their best for about a week between milk changes (BCCDC kefir guide).

Every 7 days: fresh milk

• Strain the grains with a clean, dry strainer. Plastic and stainless steel both work well.
• Pour the old milk away. After a week in the fridge it is very sour. It has fed the grains and done its job.
• Cover the grains with fresh milk, close the lid and put the jar back in the same spot.
• Lots of clear whey before day 7? Change the milk a little sooner.
• Look at the colour each time. Healthy grains are white to creamy yellow. If the grains or the milk turn pink, red, green or black, throw everything away.

Coming back: wake the grains up

Grains from the fridge are sleepy. They need a batch or two to get back to their usual pace.

1. Strain the grains and pour the resting milk away. If you like, rinse them gently with a little fresh milk.
2. Use less milk for the first three batches. Choose “Sleepy” grains in the kefir calculator and it works out the amount for your room temperature.
3. Let fridge-cold milk warm up for an hour or two. Ferment at about 24°C, out of direct light.
4. Give the first batch or two more time. They may be thinner or taste a little different. Drink a batch once it is thick and pleasantly sour like your usual kefir.
5. Allow each batch up to 36 hours. If it still looks like milk by then, pour that milk away, keep the grains and use less milk next time.
6. Add more milk slowly once the grains ferment at their usual pace again.

Still slow after a few batches? Read how to revive tired grains.

Taking the grains with you, or leaving them with a friend

• On a trip: put the strained grains in a food container or a leak-proof bag with a little milk. At your destination, ferment them in local fresh milk. New milk can give the kefir a slightly different taste.
• Flying: pack the grains in your checked luggage, sealed against leaks. Check the dairy import rules of the country you fly to before you pack.
• With a friend: a friend who makes kefir can keep your grains fermenting while you are away. Collect them when you are back.

Taking a short break is part of making kefir. The basics are also in the taking a break section of our kefir-making guide.

Kefir every day, even while your grains rest.

Our original milk kefir is fermented with living kefir grains and has no added sugar. Every 100 g contains 4.0 g of protein and 110 mg of calcium; calcium helps maintain the normal development and health of bones and teeth.

Shop original milk kefirSee live kefir grains

Frequently asked questions

How long can kefir grains stay in the fridge?

Up to a month, covered in fresh milk in a closed jar. Change the milk about every 7 days.

Do I need to change the milk while I am travelling?

For a trip of up to a month, use a bigger jar with more milk and change it when you are back. At home, change it every 7 days.

What do I do with the milk the grains rested in?

Pour it away. It turns very sour in the fridge, and your next fresh batch tastes much better.

Why is my first batch after the fridge so thin?

The grains are still waking up. Use less milk for the first three batches, and the kefir thickens as they get back to their usual pace.

Should the jar have a lid or kitchen paper in the fridge?

A closed lid. Kitchen paper with a rubber band is for fermenting at room temperature.

Does the fridge harm the grains?

The cold simply slows them down. Kept covered in fresh milk, they wait for you for up to a month.

Live kefir grainsSee them