Or, how to make yogurt and buttermilk at home.
We’ve made our own yogurt for several years now now. It’s cheap and easy, especially when you don’t rely on commercial starter culture, but rather yogurt from the store as a starter. My current batch has been going for over a year now, almost two. In Liberia, we had a culture going for a solid two years without any problems.
I’ve used a couple of different methods, but the key is to control the temperature of both the milk and the environment for the culture to work.
In Liberia, we used whole cream powdered milk (which is nearly impossible to find at a reasonable price here). I would reconstitute it at about one and a half strength, using water at about 115 degrees. The goal is to have the milk between 110 and 115 degrees when the yogurt culture goes in. I then put this container in a cooler with a damp dishtowel that I had warmed in the microwave, and leave it over night. After a couple of hours in the fridge, the yogurt had set quite nicely.
Currently, I use whole milk from the store. Even though I don’t need to pasteurize it (in Ashgabat, since we bought milk in the market in 1-liter bottles pasteurization was a necessary first step), I find I get the best set by taking the milk up to 180 degrees. I suspect that this does two things: 1) takes care of any stray bacteria that might interfere with the yogurt culture and 2) denatures and concentrates the milk proteins so that it’s easier for the yogurt bacteria to do its thing. After the milk hits 180, I cool it to 115, and pour it into a container for a water bath yogurt warmer. The heating element keeps the water at just the right temperature to gently warm the cultured milk. In about four hours, the yogurt is done, and just needs to cool in the fridge for a couple of hours to be fully set.
I recently started culturing buttermilk It started because I wanted to do buttermilk biscuits with breakfast on Sunday during Lent (rather than coffee cake). I’ve kept some around for pancakes and other baking use, and, since it’s so easy to do, well worth it. Again, starting from store-bought, it’s a ratio of about 1:3, that is, fill your container one quarter of the way with buttermilk, then the rest of the way with whole milk [it might work with 2% or skim, but I haven’t tried it] and leave it at room temperature, loosely covered, for at least eight, or up to 12 hours. What you’re looking for is the milk to get thick and start to smell slightly tangy like buttermilk. I’ve heard some people leave it for a full day, but I start to get separation after much more than 8 hours, especially when it’s warm.
I also tested whether the warming the milk to 90 degrees before culturing made a difference (which I had read on a couple of sites), but I found that the straight-from-the fridge milk cultured just as fast as the 90 degree milk.
Cheesemaking is also enjoyable, but for now, the return on investment for the time and effort is much better for just the yogurt and buttermilk. If we’re ever in a place again where all we can get is raw, unpasteurized milk from questionable sources, we’ll probably take up cheesemaking again, and add it to our regular repertoire of milk manipulation.