I've always gone with 42 degrees or better. Not sure if there is any science in there or if that number was just passed down to me. I feel like a Google wait a min....

This came up first from the Purdue University Animal Sciences, I think they should qualify.

Storing Uncooked Meat
Meat should be stored at a low temperature to help preserve its quality and prevent the growth of illness causing bacteria. Chilling meat to below 40° F is recommended. Meat can be chilled or frozen. In order to freeze meat, you must drop the temperature below 28° F.

There we go!