Principles of food preservation

Principles of food preservation

The activities of food deteriorating agents depend on various factors and that change in any of factor would result in decrease their performance.

Following are some basic principles of food preservation based on understanding how chemical reactions, physical changes and pest attack collectively reduce the food quality.

·      Prevention of autolysis

·      Prevention of microbial activities

·      Control of pest activities

·      Reduction in physical defects

1.                        Prevention of autolysis

Autolysis in food may be reduced or prevented by the inactivation of enzymes or handling of food in such a manner so as to control the reactivity of chemically active substances.

·      Change in PH

Enzymes work best at specific PH range. Enzymes are very sensitive to PH range that is specific to every food to perform their activity. By altering the PH various foods can be preserved. For example some fruits and vegetables can be preserved by pickling by simple altering the PH by Lactic acid produced by some bacteria. Similarly milk and meat products can be preserved by lactic acid and in some cases acetic acids can also be added.

·       Change in temperature

Enzymes require optimum temperature range for their activation. Any deviation in temperature range either at high or low temperature can inactivate the enzymes. Certain fruits and vegetables can be preserved by heating them at 100℃ for few seconds by a process called blanching. As a result of this exposure various damaging enzymes like catalases are destroyed. Blanching is commonly a pretreatment in certain food preservation methods such as canning, dehydration and freezing.

Use of low temperature can retard the activities of enzymes applied in cold storage rooms or in refrigerators. Thus refrigeration process delay ripening process in fruits. Freezing inactivates the enzymes and sometimes destroy them. Frozen foods have much higher shelf life than fresh ones.

·       Reduction in moisture

Enzymes require optimum moisture content for their biochemical reactions in food. Lowering the moisture or maximum removal of water will not help in the reactions of enzymes. For this reason many foods can be preserved simply by removing or binding of moisture content. Moisture in food can be reduced by sun drying, dehydration, concentration

·      Good manufacturing practices

Chemically induced autolysis can be reduced by utilizing good manufacturing practices (GMP) based on experiment and scientific knowledge. Most chemical reactions are retarded by using low temperature, by chemical inhibitor and by proper packaging.

Non-enzymatic changes can be prevented by the use of some chemicals such as sulphites to inhibit color changes or antioxidants to control rancidity. Moreover further control can be attained by using low temperature, checking water activity in dehydrated foods, reduction of reducing sugars in potatoes by storage, reduction of amino-nitrogen content in juices by ion exchange and by packaging with oxygen scavenger
Principle #2 
Prevention or delay of Microbial activity