Which freezing method uses direct contact with a cooled surface?

Which freezing method uses direct contact with a cooled surface?

• A. Cryogenic freezing
• B. Air blast freezing
• C. Plate or contact freezing
• D. Immersion freezing

Answer: (C)

Direct heat transfer by contact with a cooled surface is the key idea. In plate or contact freezing, the product sits on a refrigerated plate, so heat moves straight from the food into the plate by conduction. This solid-to-solid contact with a cold surface makes cooling rapid and often more uniform because the heat sink is large and the contact is intimate. Other methods remove heat without that solid surface touch: air blast freezing relies on cold air moving over the product and removing heat mainly by convection; immersion freezing submerges the product in a very cold liquid or bath, so cooling occurs through contact with liquid rather than a solid plate; cryogenic freezing typically uses extremely cold fluids that surround or coat the product rather than a cooled plate.

Direct heat transfer by contact with a cooled surface is the key idea. In plate or contact freezing, the product sits on a refrigerated plate, so heat moves straight from the food into the plate by conduction. This solid-to-solid contact with a cold surface makes cooling rapid and often more uniform because the heat sink is large and the contact is intimate. Other methods remove heat without that solid surface touch: air blast freezing relies on cold air moving over the product and removing heat mainly by convection; immersion freezing submerges the product in a very cold liquid or bath, so cooling occurs through contact with liquid rather than a solid plate; cryogenic freezing typically uses extremely cold fluids that surround or coat the product rather than a cooled plate.