Refrigeration

Principle

Refrigeration , process of lowering the temperature and maintaining it in a given space for the purpose of chilling foods, preserving certain substances, or providing an atmosphere conducive to bodily comfort. Storing perishable foods, furs, pharmaceuticals, or other items under refrigeration is commonly known as cold storage. Chilling slows down microbial activities and chemical changes resulting in spoilage .

In chilling, food is kept at 0^oC - 4^oC.

refrigerator

Things in refrigerator

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Disadvantage

Some spoilage microorganisms (psychrophiles) may still alive, so the food cannot be stored for long time.

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Different between refrigeration and freezing

A. Refrigeration

1. Provides cool storage of foods at temperatures ranging from 0^oC to 4^oC.
2. Water in the food is not frozen

a. Consequently, the shelf life of perishable products is extended only for days or a few weeks

Growth of nearly all pathogenic microorganisms is prevented

b. However, some spoilage microorganisms (psychrophiles) may thrive

　

B. Freezing

1. Provides cold storage of foods at temperatures lower than -20^oC 
2. Most of the water in the food (about 95%) is frozen

a. Consequently, the shelf life of perishable products is extended for months and, in some cases, years

　

b. The rate of freezing is affected by several factors that may be controlled by the food manufacturer

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Examples: Chilled meat, fruit, vegetables, etc. in a refrigerator.

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