- Naturally occurring microorganisms produce many fermented milk products.
- This preservation of milk has been known to be used since around 10,000 BC.
- Soured milk, kefir, and yoghurt are three such products.
- They could be described as “cousins”.
- Lactose, the sugar, in the milk is converted into lactic acid – this is what gives them the sour taste.
Soured Milk – Kwaśne mleko or Zsiadłe mleko – is the fermented milk product that is found in Northern Europe, especially in Poland. It forms naturally from bacteria in fresh milk and these bacteria live happily in colder climates.
When we used to have farm milk at home my mother made soured milk all the time and then also made twaróg – Polish curd cheese, which is used in lots of Polish recipes – savoury and sweet.
However you cannot make soured milk from pasteurised milk at home (of course it can be made in a dairy where they will have starters).
Yoghurt – jogurt – is the fermented milk product that is found in Southern Europe and the Middle East. It forms naturally from bacteria in fresh milk and these bacteria live happily in warmer climates.
You can make yoghurt at home because you can use some bought yoghurt as a starter and some milk and then continue using your yoghurt as a starter and so on.
I have written how to make yoghurt in my post on Yoghurt & Yoghurt Cheese in 2015.
Kefir – is similar to yoghurt though usually it is not as thick. A mixture of lactic acid producing bacteria, acetic acid producing bacteria and yeasts are involved in its formation.
I know you can get “grains” for making your own kefir although I have never tried.
I buy kefir from my local Polish shops and discovered recently that the large Tesco supermarket near me stocks it (In fact it is a Polish product!).
Recently I was given a recipe from an old Polish cookery book for a chocolate cake using kefir – I have tried this out – this and more kefir cake recipes will be posted soon.