Food Preservatives

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Introduction
A preservative is a naturally occurring or synthetically produced substance that is added to products such as foods, pharmaceuticals, paints, biological samples, wood, etc. to prevent decomposition by microbial growth or by undesirable chemical changes. All food products except for the one growing in our kitchen garden have food preservatives in them. Every manufacturer adds food preservatives to the food during processing. The purpose is generally to avoid spoilage during the transportation time. Food is very important for the survival, so food preservation is one of the oldest techniques used by human beings to avoid its spoilage. Different ways and means have been found and improved for the purpose. Boiling, freezing & refrigeration, pasteurizing, dehydrating, pickling are the few traditional ways. Sugar, mineral salt and salt are also often used as food preservatives. Nuclear radiation is also being used now as food preservatives. Modified packaging techniques like vacuum packing and hypobaric packing also work as food preservatives. Preservative food additives can be used alone or in conjunction with other methods of food preservation. Preservatives may be antimicrobial preservatives, which inhibit the growth of bacteria or fungi, including mold, antioxidants such as oxygen absorbers, which inhibit the oxidation of food constituents. Common antimicrobial preservatives include sorbic acid and its salts, benzoic acid and its salts, calcium propionate, sodium nitrite, sulfites like sulfur dioxide, sodium bisulfite, potassium hydrogen sulfite, etc. and disodium EDTA. Antioxidants include BHA, BHT, TBHQ and propyl gallate. Other preservatives include ethanol and methylchloroisothiazolinone. FDA standards do not currently require fruit and vegetable product labels to reflect the type of chemical preservative(s) used on the produce. The benefits and safety of many artificial food additives (including preservatives) are the subject of debate among academics and regulators specializing in food science, toxicology, and biology.

Importance of food preservation
Food Preservation is basically done for three reasons
* To preserve the natural characteristics of food
* To preserve the appearance of food
* To increase the shelf value of food for storage
Types of food preservatives
* Natural Food Preservatives
* Chemical Food Preservative

Natural Food Preservatives
In the category of natural food preservatives comes the salt, sugar, alcohol, vinegar etc. These are the traditional preservatives in food that are also used at home while making pickles, jams and juices etc. Also the freezing, boiling, smoking, salting are considered to be the natural ways of preserving food. Coffee powder and soup are dehydrated and freeze-dried for preservation. In this section the citrus food preservatives like citrus acid and ascorbic acid work on enzymes and disrupt their metabolism leading to the preservation.

Sugar and salt are the earliest natural food preservatives that very efficiently drop the growth of bacteria in food. To preserve meat and fish, salt is still used as a natural food preservative. Some Types of Natural Food Preservatives

1. Canning
This involves boiling the food in the container to kill all the bacteria and sealing the can to prevent any new bacteria from getting in. This sterilizes the food so it will keep for a long period. Once you open the can, bacteria can enter and begin attacking the food, so you have to refrigerate the contents after opening and use within the recommended time. 2. Freezing and refrigeration

Freezing does not destroy spoilage organisms but it stops their growth as long as the food is kept at -180C. Any bacteria present will become active as the food thaws so it is safe to thaw the food in the refrigerator. Any remaining food would then be kept in the refrigerator to slow the growth of organisms. Refrigeration will slow down the growth of...
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