why are foods frozen at a room temperature below zero?

Answer 1

Freezing only slows the deterioration of food and while it may stop the growth of micro-organisms, it does not necessarily kill them. Many enzyme reactions are only slowed by freezing. Therefore it is common to stop enzyme activity before freezing, either by blanching or by adding chemicals.

Foods may be preserved for several months by freezing. Long-term freezing requires a constant temperature of -18 °C (0 degrees Fahrenheit) or less