How do you store new kefir grains?

Quick Answers

There are a few key things to keep in mind when storing new kefir grains:

  • Store grains in fresh milk or whey in an airtight container in the refrigerator
  • Change out the milk or whey every 1-2 weeks
  • Do not freeze grains for long-term storage as this can damage them
  • Let grains come to room temperature before using again after refrigerated storage

Choosing a Storage Container

The first step in properly storing kefir grains is choosing an appropriate storage container. The container should be airtight to cut off airflow and prevent contamination or drying out of the grains. Glass jars or plastic containers with tight-fitting lids work well. Make sure the container is big enough to hold the amount of grains and milk or whey you will be storing. For small batches of grains (up to about 2 tablespoons), a pint-sized jar is ideal. For larger amounts, choose a quart-sized or half-gallon container.

Glass Jars

Glass jars allow you to easily see the grains and monitor their activity. Look for jars with wide mouths for easy access. Make sure there is enough headspace at the top so contents don’t overflow when fermenting. The lid should fit tightly to prevent air exchange. Regular mason jars or swing-top jars with rubber gaskets work very well. If using metal lids, you may want to place a piece of plastic wrap over the top under the lid to further protect against any metal transfer.

Plastic Containers

Plastic containers should be food-grade and BPA-free. Look for thick, durable plastic that will not crack or warp in the refrigerator over time. Make sure lids provide a tight seal. Yogurt containers and cottage cheese containers are good options that often come with leak-proof lids. You can also use deli containers or plastic containers made specifically for fermenting foods.

Choosing a Liquid

Kefir grains need to be stored in a probiotic liquid to keep them fed and alive. You have two options – milk or whey. Fresh milk is best as it provides proteins and sugars to feed the grains. Cow, goat or coconut milk all work well. If using cow’s milk, try to choose organic whole milk when possible. Replace the milk every 1-2 weeks to provide fresh food for the grains.

Whey is the yellow liquid left over after making cheese or strained kefir. Whey contains less sugar than milk but still provides food for the grains. Change out the whey about every 1-2 weeks as well. To store in whey long-term, refresh with milk every 1-2 months to replenish food sources.

Using Milk

Use fresh, whole milk if possible. Making sure the milk is fresh ensures the quality is high. Whole milk provides more nutrition for the grains than lower fat options. If you only have access to 2% or skim milk, the grains may grow more slowly but can still survive short-term.

You can use pasteurized or raw milk. Raw milk contains more beneficial bacteria so is ideal, but pasteurized works fine too. If using pasteurized milk, you may want to culture it with a bit of existing kefir first to reintroduce good bacteria.

The ratio of milk to grains will depend on how much you are storing. A good rule of thumb is 1 cup of milk per tablespoon of grains. Allow extra headspace for the milk to ferment and expand while stored.

Using Whey

Whey provides food for the grains while limiting fermentation. This makes it a good option for long-term storage. As with milk, use a 1 cup whey per 1 tablespoon grains ratio. You may need to top off evaporated whey with fresh whey or milk every 1-2 weeks.

Make whey by straining plain kefir or soft cheese curds. To strain kefir, place in a fine mesh strainer or cheesecloth. Allow the whey to drip out into a bowl below. Refrigerate and use within 1-2 weeks.

Storing Grains Short-Term

For short-term storage of up to 1-2 weeks, storing grains in the refrigerator is ideal. This slows fermentation but keeps the grains alive. Follow these steps for proper refrigerated storage:

  1. Fill your storage container with fresh milk or whey, following the ratio above.
  2. Add your kefir grains and mix gently.
  3. Cover the container tightly.
  4. Refrigerate.
  5. Change out the milk or whey weekly.
  6. Remove grains from the refrigerator and let come to room temperature before making kefir again. This may take 8-12 hours.

During storage, the grains may separate from the milk, forming clumps or rising to the top. This is normal. Gently stir or shake to redistribute before changing the milk or whey.

Signs of Healthy Grains

Even when refrigerated, active grains will continue to slowly ferment. Signs your grains are healthy include:

  • A tangy, yeasty smell
  • Bubbles or carbonation building up
  • The liquid separating into curds and whey
  • The grains growing in size

Signs of Unhealthy Grains

If grains are kept too long without fresh milk or whey they can become weakened. Signs your grains may be stressed include:

  • A very sour smell
  • Slimy texture
  • Change in appearance or color
  • Failed or very slow fermentation when making kefir

To revive unhealthy grains, change the milk or whey and allow 1-2 weeks refrigerated before using again. Adding a bit of probiotic powder or an enzyme supplement can also help.

Storing Grains Long-Term

For long-term storage of more than 2 weeks, you have a few options. The goal is to slow fermentation as much as possible to extend viability.


The simplest method is continuing to store in the refrigerator as described above. Just change out the milk or whey about every 1-2 weeks. The grains may gradually become less active but will remain alive for months.


Storing kefir grains in the freezer is controversial. Some sources advise against freezing at all costs while others say it can be done safely. If freezing, here are some tips:

  • Place grains in milk or whey in an airtight container, making sure there is ample headspace.
  • Freeze quickly by placing the container right against the freezer wall.
  • Thaw slowly by moving to the refrigerator 1-2 days before use.
  • Be very gentle with grains when thawing, as they will be fragile.
  • Only freeze once if possible, as multiple freezings increase damage.

Freezing too slowly, storage below 0°F, or allowing grains to thaw at room temperature can harm their viability. Freeze for no longer than 3-6 months.


Another long-term method is drying the grains. This drastically slows metabolism and creates a dormant state. To dry grains:

  1. Drain whey or milk and let grains air dry for a few minutes.
  2. Spread in a thin layer on parchment paper or a dehydrator tray.
  3. Dry at 95-115°F until hard and brittle, 6-12 hours.
  4. Store in an airtight container in a cool, dark place.

When ready to use, rehydrate by soaking in milk or whey for 12-24 hours. Change the milk or whey several times in the first week to fully revive.

Storing Kefir Made from Grains

In addition to storing the grains themselves, you may want to store kefir you’ve made from the grains. Follow these tips for storing kefir:

  • Cover tightly and refrigerate plain kefir for up to 2 weeks.
  • Flavor and store in an airtight container up to 1 week.
  • Freeze for up to 3 months.
  • Culture vegetables or make a second ferment for added shelf life.

Properly stored kefir retains more nutrients and probiotics. Never leave kefir out at room temperature or mold can develop quickly. Consume within a few weeks for best quality.

Troubleshooting Storage Problems

Even with proper storage methods, problems can arise. Here are some common issues and how to address them:

Grains not growing or fermenting well

  • Try changing the milk or whey to provide fresh food.
  • Soak in milk with probiotic powder added.
  • Culture the milk first before adding grains.

Grains smell bad or appear slimy

  • Discard milk or whey and replace with fresh.
  • Decrease storage time before changing milk/whey.
  • Clean jar and use fresh milk/whey.

Kefir over-ferments in storage

  • Consume faster or store in smaller batches.
  • Refrigerate after 12-24 hours fermenting.
  • Remove some grains to slow fermentation.

Mold develops

  • Check for air leaks and ensure lid is tight.
  • Replace milk/whey more frequently.
  • Discard moldy kefir. Mold on grains may require discarding.

With some trial and error, you can find the best methods for storing your grains to maintain viability and quality. Be patient, as each batch of grains has its own optimal needs.

Key Takeaways

Storing kefir grains properly helps preserve fermentation strength and viability during short and long-term storage. Follow these best practices:

  • Use an airtight glass or plastic container with fresh milk or whey.
  • Refrigerate for storage up to 2 weeks.
  • Change milk/whey every 1-2 weeks.
  • For long-term storage, continue refrigeration or consider drying.
  • Avoid freezing when possible.
  • Store finished kefir beverages properly as well.

With the right technique, you can have fresh kefir grains ready to make health-boosting kefir for months to come!

Frequently Asked Questions

Here are answers to some common questions about storing kefir grains:

Can I store grains without changing the milk?

It’s best to change the milk or whey every 1-2 weeks. The grains will consume the sugars and nutrients, so fresh milk provides ideal food.

What temperature should I store grains at?

Refrigerator temperature, around 35-40°F, is ideal. Higher and fermentation speeds up. Lower than freezing may damage grains.

How do I revive grains that have been stored a while?

Soak in fresh milk for 12-24 hours, changing the milk halfway. Then let ferment 1-2 more batches before drinking.

Can I use powdered milk for storage?

Yes, reconstituted powdered milk works for short-term storage. Change it out for fresh milk periodically.

Is storing in water ok?

Water alone does not provide enough food for long-term viability. Use water mixed with milk, juice or sugar for short-term storage up to 1 week.


Proper storage helps maintain kefir grains between uses. With the right container, liquid, and techniques for your timeframe, you can keep grains alive for weeks or months. Refrigeration, changing the milk weekly, and limiting air exposure are key. Follow these guidelines for storing grains and making tasty kefir anytime.

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