Why do some things need to be preserved at -190C (liquid nitrogen) or at -80C (dry ice), while others can be kept at -20C?
Can you just keep things longer if they’re frozen colder? I know that frozen plasma lasts a year in a -20C freezer, and frozen sperm can be kept for years in liquid nitrogen, but is this because of the temperature or because of the nature of what we’re freezing?
I know there are good reasons for the different temperatures, but I can’t really figure it out.
I know if you freeze beef at -35°F for a month, it turns to mush when you defrost it. I know someone that bought a freezer at a GSA auction, it was designed to freeze stuff much colder than the standard 0°F used by standard home freezers. He put a bunch of meat in it and for the first few weeks the meat was fine. Then he began to notice meat wasn’t near as good and after a month it could hardly be cooked when defrosted. It does work great for ice cream and he says he can take a 6 pack of beer from room temperature to ice cold in 5 minutes.