I always use raw milk. However, I know my milk source and the milk went from 102 degrees (from the goat) to 40 degrees in under an hour. That's crucial, so that you don't have any bacteria growing in it.
If you're making hard cheeses, raw milk is great. According to the health officials, it's completely safe if aged over 60 days.
If you're making soft (unripened) cheeses, it's recommended to pasteurize raw milk before consuming.
I've only pasteurized once, because I was serving it to friends and didn't want to risk anybody getting sick, or to admit I was serving them unpasteurized milk. I did it at the lowest temperature I could (I think it was 135, but I'd have to check) for 30 minutes. I didn't notice any change in flavor or texture.
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