A freezer tunnel is a section of a factory production line in which food is flash-frozen as it travels along a conveyor belt through an intensely cold chamber. Blast air at around −35 °C to −40 °C — or, in cryogenic tunnels, nitrogen or carbon dioxide vapour — strips heat from the product in minutes rather than hours. Rapid freezing forms small ice crystals that do minimal damage to cell structure, so texture, drip loss, and flavour survive far better than with slow freezing. Tunnels handle everything from peas and prawns to bakery products and ready meals, often as individual quick freezing (IQF) where pieces freeze separately and stay free-flowing. Continuous operation suits high-volume lines, with hygiene and defrost cycles built into the design.