Milk Kefir is a fantastic, simple way to increase the nutritional value of milk and even change it into a form that lactose intolerant folk like myself can drink.
Like Water Kefir, Milk Kefir is a group of microbes that hang together in rubber grains. Each grain is a colony in its own right and the microbes live by eating the sugars such as lactose in milk. They excrete carbon dioxide, a teeny amount of alcohol and some compounds that are great for our health, in particular, for the health of out gut biome. As they live, work and party, they produce a thick, slimy, even ropy substance that will settle at the bottom of the container – it’s called ‘kefiran’.
Little could be simpler than farming Milk Kefir.
Just keep your grains in a jar with a couple of cups of milk and every day strain the grains out. Replace the milk with fresh stuff and add the grains again. When straining, you may need to work the mix gently with a spatula or spoon. This helps the curds and whey get through the mesh of the strainer why allowing you to keep the grains separate.
Leave your grains in the milk overnight, or if you like a stronger taste, leave for a couple of days. The milk will thicken to the consistency of buttermilk. I like the taste after I’ve left it 2 days throughout most of the year but that can vary with the temperature. If you leave it too long, the milk will separate into curds and whey. You can still use it at this stage as whey is very nutritious in its own right or you can strain out the curds and squeeze them out into a very strong soft cheese. It’s magic on the garden too, if you’re not game to eat it at this stage!
You can get bubbly milk kefir through a process called ‘secondary fermentation’. You just need to put your strained off kefir into a sealed bottle for a couple of days. When you open the lid, you will be greeted with a his of escaping gas and maybe an overflow of bubbles. The kefir in the bottle (and maybe all over your bench top ) is now light and bubble with all of the extra carbon dioxide produced during the secondary fermentation process
There is some superstition around Milk Kefir. It is said not to let it come in contact with metal. This is only partially true. When straining and separating the grains from the Milk Kefir liquid, it is OK to use a metal strainer and a spoon. The trouble with metal comes in when you are fermenting the milk or storing the liquid or grains. The acids and other substances created during the fermentation process can corrode metal and introduce metal compounds into the liquid, contaminating it and harming the culture. Of course, this only happens in microscopic amounts, it won’t eat a hole through the side of your favorite pot, but, we are talking about a culture of living microbes and a tiny amount can cause a lot of grief. Don’t ferment or grow in metal vessels.
If you’ve made too much fermented milk or plan to be away for a while, it’s easy to look after your Kefir. Just put it in a jar with fresh milk and leave it in the fridge until you come back. This also gives it a rest, it’ll eat some of the goodies in the milk but not produce any fermented milk while the temperature is too low for much microbial activity. You can also dry or freeze the grains if you’ll be away a very very long time.
You can also make a tasty soft cheese from Milk Kefir with little extra effort. Take a look here.
You can find out about other simple types of kitchen fermentation on our fermentation page