Little amount of water may be added (glazing) to increase heat transfer and prevent freezer burn.
- Air blast freezer: use with expensive products: spiral or fluidised bed system.
- Immersion: use brine/sea water/ CaCl2/propylene glycol as refrigerant. T = -15 to -30 0C.
- Cryogenic freezing: LN is used in particularly with shrimp