What temperature should regulation hockey pucks be stored at?

For my science fair project I decided to see what temperature i should keep hockey pucks at in order to eliminate bounce. I was wondering what temperatures to keep them at just to try. I know it should be cold, but just how cold? I still want them to be safe to play with so its not like playing with a rock, you know? Do you have any suggestions on temperatures to try in degrees Celsius?|||Im gonna say a least 32 degrees