INDUSTRIAL-SCALE: Food Freezing

摘要

Freezing preserves raw or prepared foods to allow them to be stored for an extended period. Placing food in a frozen state slows decomposition by converting residual moisture to ice, inhibiting the growth of most bacterial species, and locking in important sensory attributes like taste, color and essential nutrients.On an industrial scale, two options typically are used for food freezing: 1.Mechanical freezing systems utilize refrigerants to cool coils that lower the circulating air temperature. That cold circulating air is used remove heat from the food products. 2.Cryogenic systems remove heat through direct impingement with the food product. Cryogenic systems use either liquid nitrogen gas or liquefied carbon dioxide as well as circulating gas vapors to extract heat quickly from the food products.Freezing or chilling is all about time, temperature, convection and conduction. Using descriptions from familiar home-life scenarios can help explain the concepts.