By- Meena Ganagani,Practicing Clinical Nutritionist,Mumbai.
Preservatives may be added to food to prevent the growth of fungi. Preservative food additives can be used alone or in conjunction with other methods of food preservation. (1)
Food preservatives are classified into two main groups: antioxidants and antimicrobials. Antioxidants are compounds that delay or prevent the deterioration of foods by oxidative mechanisms. Antimicrobial agents inhibit the growth of spoilage and pathogenic microorganisms in food. (2)
Food preservation has been around for centuries. It began in ancient times with the use of salt on meats and fish. Later, sugar was used in canned foods and humans began pickling vegetables. While all of those older methods are OK in moderation, today’s new chemical means of preservation are growing more and more abundant and are harmful to our bodies.(3)
Safety of Preservatives in Food
The use of preservatives in food products is strictly studied, regulated and monitored by the U.S. Food and Drug Administration (FDA). Federal regulations require evidence that food additives are safe for their intended use.
Preservatives in foods are subject to ongoing safety review by FDA as scientific understanding and methods of testing continue to improve. (4)
Food preservatives are classified as:
- Class I preservatives or the natural preservatives such as salt, sugar, vinegar, syrup, spices, honey and edible oil and
- Class II preservatives or the chemical preservatives such as benzoates, sorbates, nitrites and nitrates of sodium or potassium, sulfites, glutamates, glycerides and the like.(5)
Natural food preservatives
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.
Other natural preservatives in the category are alcohol, vinegar, etc. These are the traditional preservatives in food that are also used at home and while making pickles, jams and juices, etc. The freezing, boiling, smoking and salting also considered being the natural ways of preserving food. Coffee powder and soup are freeze-dried for preservation.
Chemical food preservatives
Chemical food preservatives have also been used for quite some time now. They seem to be the best and the most effective for longer shelf life. According to the International Institution of Health, here are some of the chemical food preservatives that are widely used-
- Benzoates (such as sodium benzoate, benzoic acid)
- Nitrites (such as sodium nitrite)
- Sulphites (such as sulphur dioxide)
- Sorbates (such as sodium sorbate, potassium sorbate
Antioxidants are also the chemical food preservatives that act as free radical scavengers. In this category of preservatives in food comes Vitamin C, BHA (butylated hydroxyanisole), bacterial growth inhibitors like sodium nitrite, sulfur dioxide, and benzoic acid.
Then there is ethanol that is one of the chemical preservatives in food, wine, and food stored in brandy. Unlike natural food preservatives, some of the chemical food preservatives are harmful. (6)
Artificial preservatives are chemical substances added to foods. These substances may be sprayed on the outside of a food, or added to foods in medications. Artificial food preservatives are subdivided into antimicrobial agents, antioxidants and chelating agents. (7)
Adverse effects of preservatives
Though preservatives are a beneficial to packaged food, they do have some negative effect on human health. All preservatives cause hyper activity on regular usage. Some of the common preservatives and their harmful effects on human health are listed below:
- Nitrates and Nitrites: For curing of meat products these additives are used. But sometimes it reacts to cause urticarial, itching and anaphylaxis in human beings. Sodium Nitrite is used in meat product during cooking to prevent botulism, but during high heat it reacts with the proteins to produce carcinogenic N-nitrosamines which are linked to different forms of cancers such as liver cancer, intestinal cancer and oesophageal cancer.
- Benzoates: Benzoate contained foods are strictly abandoned for asthma patients because it worsening the condition. Benzoates are also reported to cause rhinitis, chronic urticarial and flushing in some cases .Sodium benzoate which is used to enhance the self-life for a long time is found to form carcinogenic benzene while use with vitamin C or ascorbic acid. Though the amount of benzene form is low but it is a risk factor to cause cancer. It is also reported that benzoates can cause brain damage.
- Sorbates: Sorbates can cause urticarial and contact dermatitis in some cases.
- Sulphates: Copper sulphate is generally used in coloring of peas and other vegetables. It is found that the copper, when added to the vegetables, forms a compound which is not easily soluble in the human body.(8)