Home-Made Soured Milk
Soured milk is another fermented dairy product that can be made at home with very little effort. The German word for it is Dickmilch which means "thick milk". In Germany, it has lost a lot of its popularity to yoghurt but it can still be found in many supermarket shelfs. It is quite similar to yoghurt in taste and consistency but contrary to yoghurt it is very simple to make, even at home.
The biochechemical processes involved in the production of soured milk differ significantly from Yoghurt and rather resemble those of crème fraîche, that we have recently made as a base for home-made sour cream butter.
The production of soured milk has a long history and used to happen more or less uninentionally. Before the invention of the refrigerator, milk used to become sour very quickly. That usually happened before the milk was used up. Contrary to today's practice, sour milk was not thrown away but used as a cooking or baking ingredient or it was simply eaten with sugar.
You should, however, not drink or use adulterated pasteurized milk. It may taste sour but that sourness does usually not come from lactobacillales. Throw it away and use fresh milk for making soured milk. The recipe is ridiculously simple.
For ca. 550 g soured milk
- 500 ml pasteurized milk
- 50 ml buttermilk, not pasteurized
ca. 3 minutes for preparation, up to 72 hours fermentation time
- Mix the milk with the buttermilk and let it sit in a clean, sterilized closed vessel at 25-30 °C for ca. 36-48 hours. Do not move or shake!
- Transfer into the fridge, when the soured milk has the desired consistency. Wait at least 24 hours before serving.
The exact times and quantities are a matter of experience and also depend on the products used.
Fresh, unpasteurized milk already contains enough lactobacillales and you can theoretically omit the buttermilk. Adding it still helps the desired lactobacillales to prevail over other bacteria and prevents the soured milk from adulterating.
Do not believe the urban legend that fresh, untreated milk is healthier than pasteurized milk. Unpasteurized milk is even a serious risk for babies and toddlers. Adding the wanted bacteria to pasteurized milk is a lot simpler and safer. Raw milk contains a cocktail of microorganism that can easily spoil the products. Pasteurized milk on the other hand contains everything that the desired lactobacillales need for their metabolism.
Finding the right buttermilk can be a little bit of a challenge. It should contain enough lactobacillales to get the reproduction started. I have achieved the best results with Ja! Buttermilk. Other, a lot more expensive products seem to not contain lactobacillales.
You can also experiment with crème fraîche or sour cream as a base for the fermentation. Once successful, you can also use a little leftover of your own, home-made soured milk as the base for the next portion. But you have to keep an eye on the consistency and taste and start a new culture if you have the impression that your old one contains too much other, unwanted microorganisms.