Eli5: How does freezing food at -5 or -15°C make a difference, if water already freezes at 0°C?

Question

Hi! While unfreezing my ice box I put various groceries on the porch, as it is around -5°C at the moment. When I checked the packaging, I noticed that the date the food was supposed to be consumed by, varied widely, depending on the temperature. From 3 days (-5°C) to around a year (-15°C). How does it make that big of a difference? Is the water not equally frozen at both temperature points?

In: 4

Answer 1

Bacteria grows quicker at -5 degrees than at -15 degrees. Cells are made of more than just water so they can still be functional below the freezing temperature of water