The general rule for safety is, 4/40. The food, no matter what, should not be over 40 degrees for 4 hour total not each time. So if you have fresh meat (never frozen) and it takes two hours to get it below 40, you then have two hours safely later above 40. At least that is what is taught in Rest. cert. courses as I remember it. Also, as far as cooking temp goes, your main goal is over 140 degrees. 99% of bacteria dies at this temp, so for the most part you will be safe. The 1% remaining doesn't die until 190 degrees, which is ruined food.