초록 ▼

A cryogenic freezing method uses a mixture of liquid nitrogen and liquid oxygen in amounts approximating the composition of atmospheric air to freeze food products. The mixture preferably includes 18% to 25% oxygen and the balance nitrogen, with small amounts of residuals which are commonly found in

A cryogenic freezing method uses a mixture of liquid nitrogen and liquid oxygen in amounts approximating the composition of atmospheric air to freeze food products. The mixture preferably includes 18% to 25% oxygen and the balance nitrogen, with small amounts of residuals which are commonly found in air. The present invention involves replacing a liquid carbon dioxide or liquid nitrogen cooling medium which is used in known cryogenic freezers with a liquid nitrogen and liquid oxygen mixture. The liquid nitrogen and oxygen mixture can be used according the present invention in many of the known freezers using liquid carbon dioxide or liquid nitrogen as a cooling medium, including tunnel freezers, spiral freezers, and immersion freezers. The use of a liquid nitrogen and liquid oxygen mixture improves the efficiency of a freezer because the cold vapors are not exhausted from the freezer. In addition, the leakage of vapors from the freezer into the room air will not create unsafe conditions for workers.

대표청구항 ▼

[ What is claimed is:] [1.] A method of freezing food products with liquid air comprising:supplying food products to a freezing chamber;cooling the food products by injecting liquid nitrogen and liquid oxygen into the freezing chamber, in amounts which approximate the composition of atmospheric air;

[ What is claimed is:] [1.] A method of freezing food products with liquid air comprising:supplying food products to a freezing chamber;cooling the food products by injecting liquid nitrogen and liquid oxygen into the freezing chamber, in amounts which approximate the composition of atmospheric air;sensing an oxygen level, at at least one location inside the freezing chamber or within the room in which the freezing chamber is located; andusing the oxygen level information previously acquired to control the mixture of liquid nitrogen and liquid oxygen by modifying, when necessary, the flow rate of liquid nitrogen and/or the flow rate of liquid oxygen.