To heat or not to heat? Help me answer this question!
After reading some of the homemade yogurt threads, I am still curious about the necessity of heating the milk prior to the fermentation process. My yogurt maker includes instructions for yogurt preparation with or without heating. Is the heating step really necessary? Will not heating be detrimental to the finished product?
If your yogurt maker has instructions for unheated yogurt, why not just try it? (and then report back!)
I have made natural yogurt a number of times simply using a yogurt I liked and warm milk, with varying degrees of success. In my experience if you get the temp right, it cultures a whole lot faster and the flavour is more 'true' to the parent starter. The way I understand it, the bacteria need the warmth to grow.
The quality of my yogurt - consistency and flavor - seems to be directly related to the temperature to which I heat and then cool the milk. My yogurt maker's recipe calls for heating to 180F. I shoot for 185-190. The closer I can get it to 190 without actually boiling, the thicker the final product seems to be. As for cooling, my instructions are to cool to 110, but I usually go to about 115, add about a cup of milk to a few tablespoons of yogurt, and then mix that into the rest of the milk.
In the past, if I was in a hurry or not paying attention and either didn't heat to 180, or cooled past 110, the yogurt turned out thin, even after a 24 hour incubation.