You end up doing all kinds of incidental Arts and Sciences projects. This one started when I decided to prepare Tandoori Chicken for our cooking night at Pennsic. Naturally I wanted to do at least one test run instead of making it “cold” for the event, so I set out to acquire the ingredients.
One of the main ingredients in the Tandoori marinade is yogurt. Alas, Lord William seems to have a problem digesting cow’s milk, so Fjorleif and Juliana set out to the international groceries in search of a goat’s-milk-based yogurt.
Undeterred, we bought some goat’s milk and some yogurt with live cultures and set out to make it ourselves. The National Center for Home Food Preservation has some nice instructions on the process.
Stage one was to mix the goat’s milk and some non-fat dry milk in a double boiler and heat it to 200 degrees Fahrenheit. This stage reportedly changes the milk proteins to keep the milk from separating into curds and whey later in the process.
The next step was to rapidly cool the milk down to about 115 degrees, a temperature at which the bacterial culture that converts milk to yogurt can thrive. Once there, my lovely assistant Juliana blended some of our “starter culture” yogurt into the milk.
With the milk “inoculated”, we put it into the oven for six hours at about 110 degrees for the microbes to have their way with the milk. This turned out to be the most tedious step in the process, as I had to check the oven every ten minutes or so to try to maintain the correct temperature. The thing doesn’t even have a 110 degree setting on its dial. The temperature actually wandered quite a bit between 100 degrees and 150 degrees in the oven, but I think the milk/yogurt itself stayed pretty close to 110.
In any case, the yogurt seemed to have set reasonably well after six hours, and I transferred it to the refrigerator to cool down to the 40 degree range, which would deactivate the microbes.
This process was difficult enough with a modern stove, oven, double-boiler, refrigerator, and so forth. My mind boggles a bit at how much more complicated this must have been centuries ago when yogurt was discovered. Of course, much of this process can probably occur naturally given the right conditions; we’ve just applied science and technology to make it more consistent and reliable.
In any case, the test of the Tandoori will occur tonight, and we’ll find out how well we do as yogurt makers.