Soured Milk is a light tart beverage – a little bit like yoghurt, but better! Traditionally, it was simply fresh raw milk that was kept in a warm place for a day – often by a kitchen stove. 

Milk acidifies naturally with time, thanks to the bacteria that are already there. These cultures would slowly “eat” the lactose away. With time, they multiply throughout – acidifying the milk by releasing lactic acid. Eventually, the milk sets and forms a curd.

For the full list of ingredients & detailed instructions, please see the recipe card at the end of this post. But before you scroll, there’s important stuff to know below.

I wasn’t sure if it is not too trivial to talk about something as simple as Soured Milk, but after all, it’s a staple of Polish cuisine (perhaps a bit forgotten, but still). 

Soured Milk is a great base for many summery dishes, it works great in baking too. Plus, there wouldn’t be ‘Twaróg’ (Polish-style farmer’s cheese) without it. Give it a go, it’s easy to make at home.

Do you need any special ingredients to make Soured Milk?

You’ll need one of the following:

• Raw Milk (unpasteurised, unsterilized),
  or…
• A combo of regular, pasteurized whole milk, together with sour cream.

Raw Milk: Souring the milk is a piece of cake if we can get it fresh. Raw, unpasteurized, unsterilized – basically straight from the cow’s teat. 

🇵🇱 In Poland, raw milk is sold at farmer’s markets, mlekomats (fresh milk vending machines) or you can order it online (e.g. from Rano Zebrano, Lokalny Rolnik)

🇺🇸 Getting raw milk in the US can be a bit trickier. I hear that selling raw milk is illegal in some states. If you’re a lucky cow owner – problem solved. If you have a farm nearby – great, here’s a Raw Milk finder for your reference.

🇬🇧 In the UK, I used to buy raw milk at the farmer’s market. A quick Google search tells me that some farms offer raw milk directly in their farm stores (or with delivery). Overall, it seems selling raw milk in the EU is totally legal.

Fresh Pasteurized Milk and Sour Cream: The trick here is to acidify the regular, pasteurized milk with some friendly bacteria. That can be done with a spoonful of soured milk from before, but who has that on hand? Instead, an addition of a regular sour cream works just as well. 

When buying milk and cream, it’s worth reading the label. The list of ingredients should be as short as possible. Get the “organic” or “bio” products if you can, without any artificial additives or preservatives.

Important note: a shelf-stable UHT (Ultra-Pasteurized) milk won’t work at all. The milk will turn bitter. 

How should you serve this Soured Milk?

In Polish cuisine it’s common to serve a glass of cold Soured Milk alongside some young potatoes (baked or boiled), lightly sprinkled with chopped chives or dill.

They’re served together with eggs on the side – sunny side up. It’s a great lunch for a hot, summer day.

Can you make this Soured Milk another way?

• Some recipes mention acidifying the milk with vinegar or lemon juice – but by doing so, the beverage won’t be cultured. We would be losing out on all the beneficial probiotics. And secondly, I find that there’s a difference in flavour and texture. Subtle hint: fermented milk is sooo much better!

• If you can get cultured buttercream, you can use it instead of (or in addition to) sour cream.

What dishes can you make with Soured Milk?

Soured Milk can be used in cakes, pancakes, scones, muffins, cookies and other baked goods. Whenever you see milk, yoghurt or sour cream mentioned in a recipe – it can be substituted for Soured Milk. 

But there is more. Many Polish recipes use Soured Milk to make various ‘Chłodnik’ soups (cold soups).

It’s the key ingredient to make ‘Twaróg’ – a Polish-style farmer’s cheese. And ‘Twaróg’ goes everywhere: as a Pierogi filling, as a Crêpe filling, into ‘Leniwe’ dumplings, and crucially – into a Polish-style cheesecake.

What diets is Soured Milk suitable for?

Soured Milk is meat-free, therefore suitable for vegetarians. 

It’s also a probiotic superfood, supporting your digestive health. Try it – your gut bacteria will be over the moon. More on the health benefits of Soured Milk here.

How long can you keep this Soured Milk in the fridge?

Once the milk has soured, keep it refrigerated and consume it within 2 to 3 days.

Can I freeze Soured Milk?

No, I wouldn’t recommend freezing it. It turns grainy, fat separates from the liquid, the texture becomes uneven.

FAQ & Troubleshooting

🤔 What are substitutes for Soured Milk?

The best substitutes for soured milk are: buttermilk, sour cream or natural yoghurt (regular or Greek-style). They work well when cooking and baking.

🤔 How do you know that Soured Milk is off?

Have a taste – if it tastes bitter, that means it has spoilt. That happens sometimes, usually when:

• The temperature during fermentation was too low. If we want the bacteria to transform our milk into a delicious beverage, it’s best to keep it souring at room temperature.
• The milk (or a part of it) was in fact UHT (Ultra-Pasteurized) milk. Read the labels carefully – the ingredients list should be as short and natural as possible. Get the “organic” or “bio” type if you can, without artificial additives or preservatives.

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