Q. Use of Chemicals to Control and Destruct Microorganisms?

Ans.

The use of chemicals, as a process of food preservation, has been used since long, ever since man found them by trial and error to be beneficial to him. Sodium chloride or the common salt has been the oldest compound which has been serving the purpose since several centuries. Apart tiom sodium chloride, other chemicals which were being used include salt peter, slaked lime etc. The salt peter (sodium and potassium nitrate) in combination with common salt was used to impart flavour and keeping quality of meats. All these compounds can be termed as a preservative.

Now, then, how would you define a chemical preservative? Let us find out. A chemical preservative is a substance which is capable of either inhibiting, retarding or arresting decomposition of foods. The use of chemicals as preservative has been subjected to criticism due to their indiscriminate use and the likely hazard they pose to the human health. The process of preservation by the addition of chemicals to foods has to be undertaken, keeping in mind the usefulness and limitations in affecting human health.

International organizations, such as the Food and Agriculture Organization (FAO) and World Health Organization (WHO), have defined limits for each chemical to be used as a preservative. The Government of India regulates the use of various additives in foods. The use of chemicals has to be employed, if it is an economical means of preservation and only when other physical means like pasteurization etc. are not possible or other methods of preservation are not available. The preservative should extend the storage life of the product and at the same time, not affect the quality and be an antimicrobial agent. It also should not be converted to other toxic compounds on reaction with the food commodity. We will learn more about chemical preservatives later in this Course in Unit 7. But here we must understand how do these preservatives extend the storage life of the product. Remember, the chemical preservatives serve as antimicrobial agents by acting as growth inhibiting 'or growth retarding agents or by killing the microorganisms. The action of most chemical agents on microbes include their effectiveness either by their effect on their genetic functions by: (a) interacting with the DNA molecules (b) acting upon the cell wall (c) inhibiting the microbial cell enzymes, and (d) making the essential nutrient unavailable to the microorganisms.