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 bacteria and fungi but doesn’t stop it completely as freezing does. . Drying Drying kills or completely inactivates most bacteria, especially if it is kept in air-tight containers. Normally drying completely alters the taste and texture of the food, but in many cases (such as raisins) a completely new food is created that is flavorsome and popular in its own right. Freeze drying is a special form of drying that removes all moisture and tends to have less of an effect on a food’s taste than normal dehydration does. In freeze drying food is frozen and placed in a strong vacuum. The water in the food then sublimates – that is, it turns straight from ice into vapour.
Freeze drying is most commonly used to make instant coffee, but also works extremely well on fruits like apples. 4. Boiling (heating, including pasteurization) Food can be made sterile by heating it to over 70°C (pasteurization) with the bacteria being killed or by raising the temperature to over 120°C Ultra High Temperature (UHT). This higher temperature will kill all spores as well. Food is generally canned after heating so it will last for many months. 5. Vacuum packing This preserves food as it removes the oxygen that would otherwise support organisms that attack the food such as fungi, bacteria and insects.
As long as the package remains sealed the food will last for a much longer period of time than if it was just in the refrigerator. Chemical Food Preservatives Chemical food preservatives are also being used for quite some time now. They seem to be the best and the most effective for a longer shelf life and are generally fool proof for the preservation purpose. Examples of chemical food preservatives are: Benzoates (such as sodium benzoate, benzoic acid) Nitrites (such as sodium nitrite) Sulphites (such as sulphur dioxide)Sorbates (such as sodium sorbate, potassium sorbate.
These chemicals make food last longer on the shelf or in your refrigerator by inhibiting the growth of organisms such as bacteria or fungi. Oxidation leads to the food becoming rancid and losing color. Some are antioxidants that retard the oxidation (reacting with oxygen) of fats and oils. Some examples are: Citric acid, EDTA (ethylenediamine tetra acetic acid), lactic acid, lecithin, mono and diglycerides, polysorbate 60, propyl gallate, sodium nitrate and nitrite, and sodium benzoate. Many artificial colorings have been added to food to make them look better.
Some examples of additives that influence appearance are: artificial colourings such as Red 40 or allura red AC (food dye) used mostly in ‘junk food’, Yellow 5 or tartrazine. Many of these additives are artificial sweeteners and some enhance the natural flavours of the food. It is not understood how flavour enhancers work. Some examples are: Acesulfame-K is an artificial sweetener that is used in chewing gum and soft drinks. Aspartame (also known as Equal or NutraSweet) is used in low-cal or diet food. Hundreds of chemicals have been used instead of natural flavors.
Most are safe but they need to be used because there is little or no natural material in the food such as fruit. Companies keep the identity of their flavors a trade secret. Butylates Butylated hydroxyanisole (BHA) is an antioxidant. It is a waxy solid used as a food Additive. The primary use for BHA is as an antioxidant and preservative in food, food packaging, animal feed, cosmetics, rubber, and petroleum products. This chemical food preservative is expected to cause high blood pressure and cholestrol level. This can affect the kidney and liver function. It is found in butter, vegetable oils and margarine. BHA (butylated hydroxyanisole)
BHA is expected to cause the live diseases and cancer. This food preservative is used to preserve the fresh pork and pork sausages, potato chips, instant teas, cake mixes and many more. Caramel Caramel is the coloring agent that causes the vitamin B6 deficiencies, genetic effects and cancer. It is found in candies, bread, brown colored food and frozen pizza. Benzoates This group of chemical food preservative has been banned in Russia because of its role in triggering allergies, asthma and skin rashes. It is also considered to cause the brain damage. This food preservative is used in fruit juices, tea, coffee etc.