Pasteurizing at 161 or 140?

[Jeepyj]

I have only used store bought milk so far, but this Friday I am getting some raw goat milk for the weekend.
My book (I need more books) says to pasteurize at 161 degrees for 15 seconds but I have seen other places to pasteurize at 140 for 30 minutes.    Which is preferred and why?

[awakephd]

Both methods are intended to produce the same results as far as the bacteria are concerned. However, in theory, higher temperatures do more damage to the milk; in theory, longer times do more damage to the milk. That might make it seem like a wash between the methods -- damage it with heat or damage it with time -- but for a home-pasteurizer, trying to do 161° for 15 seconds will almost certainly involve heat AND time -- unless you have special equipment, you can't flash-heat the milk to 161° and immediately cool it down; you will heat it up over a relatively long time to reach 161°, and take some time to get it cooled back down.

Thus, most home users will go the low-temperature pasteurization (LTP) route ... OR they will skip pasteurization altogether. If you trust your milk source and how it has been handled in getting to you, you may want to use the milk raw, especially for cheeses that age 60+ days. If, like me, your only access to raw milk involves trucking in from another state, passing through several hands, and finally arriving in who-knows-what condition, you may want to LTP.

[Jeepyj]

I'm getting my milk from a mennonite family. I'm sure it's fine, but, I'm going too be giving some of the fresh cheese to my mother in law, so I'd be really bad for me if she fell ill. LTP it is.

[Mermaid]

I pasteurize at 145 for 30 minutes. Doesn't damage milk as much and no one has ever fell ill.