Principle 2

.                       2.                        Prevention of microbial activity

Food can be prevented from microbial activity by either hindering their entry into the food or if they entered than remove them physically or delaying their growth and activity if they are already preset in the food. Microorganisms like bacteria, molds, yeast, parasites and prions cause spoilage of food. By providing unfavorable conditions their activities can be prohibited.

·     Keeping Microorganisms Out

Naturally every food has outer covering that protect it from outside invaders. The skin, peel, shell and husk provide these commodities protection against infection and outside sources. In case of damaging that out covering will allow the microorganisms to enter and cause spoilage of food. To protect entry of microorganisms from an outside source protective covering is provided for the food in industries. While fruits, vegetables, meat and other foods may be packed and protected in tin cans or glass containers. Some fruits are given edible coating of wax to protect from the attack of microorganisms.

·      Removal of Microorganisms

During food processing, it is difficult to keep microorganisms away since these are omnipresent. Even without obvious signs of microbial attack, microorganisms gain entry into the food during harvesting, storage, and further processing operations. As microorganisms are too small to be seen so it is not an easy job to pick and throw them out. Bruising on fruits and vegetables can hold microflora. Therefore food processors recommend washing of raw material to remove most of microorganisms and other contaminants. The bruised, decayed and damaged portions are trimmed off during trimming operation. These operations help to reduce the microbial load in the food product and help in its preservation. In liquid beverages and drinks microorganisms can be removed with the help of filters by a process called filtration. In the brewing industry special centrifuges are used to separate yeast from beer. In dairy industry centrifugation is applied to separate cream from milk. During this process a large number of microorganisms are also separated from the milk fractions and are removed with the cream.

·      Creation of Unfavorable Conditions

Most food spoilage microorganisms are aerobic in nature. They require oxygen for their germination. This leads food technologists to create anaerobic conditions that can control growth of vegetative cells and germination of spores. This can be achieved by a process of canning using vacuum to remove oxygen in an operation called exhausting. The air from the can is removed and then sealed air tight. Hence if somehow microorganisms entered into the food they will not be able to survive and spoil the food. On the other hand anaerobic microorganisms may create a problem in these processes if their activities are not checked and destroyed.

In case if microorganisms gained entry into the food their growth can be restricted by the removal of moisture. All microorganisms require oxygen for their growth and activity. Thus if moisture content is less than its requirement then their growth can be inhibited.

The moisture can be removed from the food by dehydration, drying or by concentration of available moisture. The use of certain chemicals such as sugar, glycerin and other water binding chemicals can help in the removal of moisture.

Use of preservatives can also prevent the food from spoilage by microorganisms. For example sulphur dioxide and benzoic acid protect spoilage of various fruit juices from spoilage. Some chemicals are inherently present in the food that protects it from spoilage. Such as Lactic acid is present in the milk and meat which is produced by Lactic acid bacteria. Thus most of dairy and meat products are preserved by the Lactic acid. In some vegetable products such as in pickles lactic acid also play a significant role in its preservation. Lactic acid, basically reduce the PH of food that protect against microorganisms.

Use of temperature, is also very effective the creation of unfavorable conditions for microorganisms and protect the food. Use of low temperature below freezing will stop all the activities of food spoilage organisms.

Destruction of microorganisms

Spoilage in foods may also be prevented by destroying microorganisms. High temperatures above the maximum growth temperature have adverse effects on microorganisms. For this purpose blanching is practiced in food industries before preservation of food. Blanching is used to inactivate the enzymes. However, it also helps to kill some vegetative forms of microorganisms. Pasteurization temperatures (65℃ to 88℃) are used to destroy microorganisms including bacteria and yeast in some foods. Sterilization is also employed to destroy pathogenic organisms. However it is not possible to kill all microorganisms in the food therefore heat processing is employed. Some microbial spores remain present even at high temperatures but with the combination of other techniques in food preservation they remain dormant and cannot spoil the food.

Some chemicals are also added in the food to destroy the microorganisms such as sulphur dioxide and benzoic acid are commonly used in fruit and vegetable preservation industry.

The use of radiations of different wavelengths is also practiced to kill microorganisms. The ultraviolet waves from the electromagnetic spectrum have germicidal properties. Gamma rays, emitted from the byproduct of atomic fission are also germicidal and when applied to food, help preserve the food.
Principle #3
control of pest activities