I have often been asked about sour-milk when I have posted cake or muffin recipes. When I started baking cakes, the recipes I found called for sour-milk or buttermilk and I had never seen either of them sold around were I live. So I needed to learn how to make it myself. The great thing is that it’s really simple.
What is the difference between sour-milk (also known as soured milk) and buttermilk? Both can be used interchangeably in a cake recipe. Both terms were also used quite loosely, so I put on my Sherlock hat while I looked through many google entries on the matter and came to the following conclusion:
Sour-milk is the result of adding acid to milk.
Buttermilk has been purposefully cultured with the bacteria that produce lactic acid in the milk.
Adding acidic substances to milk makes it coagulate. The result is a thicker texture and sour taste. They are not milk that has gone off, because that would be full of toxins from the massive amount of microorganisms that has grown in the milk.
So, strictly speaking, I make sour-milk for my recipes. Simply put a few drops of lemon juice or vinegar into one cup of milk. Stir for a few seconds. Let it rest for 10 minutes. Et voilà.
Oh, yes it will look kind of yellowy and uneven, not lovely, but that is how it’s supposed to turn out.
Thank you for reading!