Food preservatives constitute a group of compounds of widely different molecular structures; they are organic and inorganic substances with different functional groups and tendencies to form ions. There are no procedures that are generally applicable to the analysis of preservatives as a class of food additive; the procedures are specific to the preservative being analyzed. The lowest concentrations of commonly used preservatives are of the order of a few milligrams per kilogram of food, and, with few exceptions, recommended or statutory methods of analysis are designed to give a good accuracy at levels of 10 to > 1000 mg of preservative per kilogram of food. The question of the lower limit of detection is rarely an issue, unless it is desired to use small sample sizes, e.g., < 1 g, or to determine whether or not a food or its ingredients had been treated with a preservative. For solid foods, small sample sizes often lead to nonrepresentative sampling and should be avoided. Not all the procedures described constitute official methods of analysis. Frequently, for routine analysis, a food manufacturer would use a rapid or cheap analytical technique standardized against an official method. The official status of given procedures varies from country to country.
Organic and inorganic acid preservatives may be added in the form of the undissociated acid or a variety of salts. In food, the ionic composition is determined largely by concentration and pH, but it is generally impossible to predict this accurately for any given situation. In order to avoid complications with the specification of the amount of preservative in a food, this is usually referred to as the weight-for-weight concentration of the undissociated acid, e.g., benzoic acid, sorbic acid, or sulfur dioxide. Nitrite and nitrate levels are expressed in terms of the weight of the sodium salt.
Chemical reactions between food preservatives and components of microbial cells, or with food components where there are implications with regard to antimicrobial action, have been described above. However, some food preservatives, and particularly sorbic acid, sulfur dioxide, sulfites, and nitrite ions are capable of more extensive reactivity with food components. This may lead to the formation of reaction products of toxicological importance and a reduction in the concentration of available 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 drops the growth of bacteria in food. To preserve meat and fish, salt is still used as a natural food preservative.
Artificial preservatives are the chemical substances that stops of delayed the growth of bacteria, spoilage and its discoloration. These artificial preservatives can be added to the food or sprayed on the food.
Types of Artificial Preservatives Food
- Antimicrobial agents
- Chelating agent
In antimicrobial comes the Benzoates, Sodium benzoate, Sorbates and Nitrites.
Antioxidants include the Sulfites, Vitamin E, Vitamin C and Butylated hydroxytoluene (BHT)
Chelating agent has the Disodium ethylenediaminetetraacetic acid (EDTA), Polyphosphates and Citric acid
Harmful Food Preservatives
Although preservatives food additives are used to keep the food fresh and to stop the bacterial growth. But still there are certain preservatives in food that are harmful if taken in more than the prescribed limits.
Certain harmful food preservatives are 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.
This chemical food preservative is expected to cause high blood pressure and cholestrol level. This can affect the kidney and live 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 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.
In addition to this there are many other harmful food preservatives. These are Bromates, Caffeine, Carrageenan, Chlorines, Coal Tar AZO Dies, Gallates, Glutamates, Mono- and Di-glycerides, Nitrates/Nitrites, Saccharin, Sodium Erythrobate, Sulphites and Tannin.