Latent heat

Water turning to ice at 0 °C releases 334 kJ per kilogram; the thermometer does not move meanwhile. Since most foods are largely water, their latent heat of freezing lies between 200 and 300 kJ/kg. The refrigeration cycle works on the same effect: the refrigerant takes up heat as it evaporates in the evaporator and gives it back as it condenses in the condenser.

In blast freezing and frozen storage projects this is the largest part of the product load. Freezing meat takes three to four times the heat of chilling the same meat from 20 °C to 0 °C. A condensing unit selected without the freezing share cannot freeze the product in time; the core temperature sits at the freezing point for hours and quality drops.