I was hoping to find a better answer here, I started experimenting with yogurt about 6 months ago, and make yogurt regularly as it's part of my diet as a weightlifter ( I go through a gallon of yogurt every 4 days). I started with regular pet brand, and now buy organic pasterized. I can't find any raw milk in my area. but it would be useless anyway because I'd kill anything beneficial to the raw milk, as the only process I've gotten to work is heating the milk to at least 180 degrees, and then cooling. I've tried several times heating the milk ,to only 140 or 160, but 8 to 12 hours later it seems like all I have is something that reminds me of spoiled milk, it has all these weird chunks in it and is watery. but when I heat a 180, then cool to 111, stir in 2 tablespoons of my last batch of yogurt, seal the lid, lock it in a cooler filled with jars of hot water,. 6 hours later I have very solid very creamy yogurt. what am I doing wrong that others seem to be okay with getting a good product without having to heat their milk so high?