Burgers are all in a whirl
15 Jan 2000
Cryogenic freezing is finding applications across the food industry; in fact, your next Big Mac could well have been frozen with liquid nitrogen. Air Products has just installed a new spray-freezing system at McKey Food Service, which supplies burgers to MacDonalds.
The freezer sprays liquid nitrogen onto burgers on a moving belt. Air Products' innovation is to install fans under the belt to create spinning vortices of cold gas above the food (see diagram). This, claims development team leader Jerry Miller, makes heat transfer from the burgers to the gas 154 per cent more efficient. Unlike non-vortex freezers, the temperature is constant across the width of the belt.
The new system, called 'Cryo-Quick VT', has allowed McKey to increase its throughput and vary the load through the freezer, while using about 20 per cent less nitrogen.
