system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does leaving food in the freezer for a long period make the food taste like 'freezer'?

...even if the food is in original, unopened packaging?
gpt
Frozen foods keep their fresh flavor because of flash freezing, where the water solidifies so fast that molecules don't have time to form regular crystals which would normally increase the volume of the ice and produce sharp, crystalline vertices, causing cells and tissues to rupture and destroying proteins and starch chains in the process. If food is placed in the freezer fresh this will occur and create a "freezer burned" taste because many of the chemical structures we have evolved to taste have been disrupted by the crystals. Flash frozen foods may become freezer burned too if they have been in your freezer long enough. The occasional temperature changes (opening the door, putting new, room-temp items in, power outages, etc.) can cause partial thawing and recrystallization, slowly rupturing cells and tissues and creating a similar effect.

For actual 5-year-old : the ice in the food makes sharp edges that break down the food over time.