No country for old milk: how kefir grains help me avoid food waste

Fermentation is a handy tool to prevent food going to waste, like milk that’s about to expire. No spills, no tears! Let’s make kefir. 

Food waste in aisle seven…

The other week in the grocery store, I noticed bottles of organic milk on sale for only a dollar each. Normally these are $5.50 at the same shop so I took home two bottles full.

The only catch? The milk would expire the next day. But don’t fret friends, I had a plan.

I would make kefir of course.

Milk kefir is a fermented probiotic food that has been shown to improve gut bacteria, which helps not only our physical health, but our mental health too.

Fermentation is a way of preserving foods that would otherwise go off. The way it works is that the acidic conditions created through fermentation inhibit the growth of bad bacteria, which keeps foods safe for us to eat. In many cases, fermentation actually makes the foods more digestible and nutritious.

The method came into play long before refrigeration was a thing. Like, well before. Because if you think about it, bread is fermented grain, fish sauce is fermented fish, cheese is fermented milk, and so on. These foods have been part of tradition cultures for eons.

Fizzy, tangy milk kefir

Milk kefir grains are a type of SCOBY that transform milk specifically into a fizzy tangy yogurt-like food. I eat it just as I would yogurt or cook with it just as I would sour cream or buttermilk. Or I make cheese – but that’s a story for another day. It’s a bit more liquid in texture than yogurt – reminiscent of Yop, for those of us who remember.

While one can buy kefir in most grocers around my parts, I make my own because it’s a better quality probiotic, I can avoid excess packaging, and it’s all just too easy.

How to make milk kefir

All you need is a few tablespoons of kefir grains and some milk. The amounts are somewhat flexible, as is the time you leave it out. Use a ratio of around 8 parts milk to 1 part grains, or reduce the ratio of milk.  I’ve been making it for over a year now and I find it to be a very robust culture that tolerates my very casual approach to following recipes.


  • Add your kefir grains to up to 1L of milk in any clean glass container.
  • Leave on the kitchen bench for 24 – 48 hours at room temp with a loose covering to keep out bugs, but not airtight. The warmer the temp, the faster the ferment.
  • After the fermentation step, strain out the grains with a fork or some other straining tool.
  • The strained kefir goes back into the same jar and into the fridge, and the grains go into more milk for a new batch in a clean jar. You can add fruit and let it sit out for a second ferment, but I haven’t experimented as much here as I have with kombucha and my super duper, mega favourite ferment, water kefir.
  • After the milk kefir has gone into the fridge with a tightly capped lid, it will become effervescent and keep for a few weeks in the fridge.

If I’m travelling or just want to press pause on making more kefir, I put the grains in milk and put them into the fridge. Refrigeration slows down the activity of the culture, and thus, the fermentation process. This is the slow train to Kefirville. If you leave this a week or so in the fridge, you’ll have the same result as if you’d done the shorter stint on the counter. I was out of the country for over three weeks last summer and it was all fine like this until I returned.

Where to find milk kefir grains

It’s cheap to make your own kefir, it’s so simple, and it’s a great way to avoid food waste.

If you’re in Australia, look for a crop swap group in your area, try asking on the Nabo app (this is where I got mine – thanks Roz!), or you could try searching this database for someone nearby. I’m sure you could buy some online or dehydrated, but sharing cultures is a way to make life better without paying to play. Once you have your grains, they will last indefinitely, and you can share with others once they start to multiply.

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