Common Preservatives

There are many ways to preserve food. Commercial sterilization destroys bacteria, while chemicals are effective in slowing the spoiling process by inhibiting the growth of microorganisms. In addition, food that is frozen, dried, smoked, pickled or canned may be preserved without chemicals. The three categories of chemical preservatives are antimicrobials, used to inhibit the proliferation of bacteria, yeast and mold; antioxidants to slow the oxidation of fat and prevent rancidity; and chemicals that block the ripening process. Scientists continue to search for natural, safe preservatives.

Nitrites and Nitrates

• Antimicrobials such as nitrates and nitrites are common in packaged meat to guard against the bacteria clostridium botulinum. Some antimicrobials are useful as antifungal agents. According to "Chemical & Engineering News" magazine, nitrites react with amino acids in the cooking process to form nitrosamines, which are cancer-causing agents. However, the level of nitrites found in cured meat is not currently a concern. Nitrates and nitrites give cured meat a pink, fresh color. Without these additives, the meat would turn brown. Benzoates or sorbates are antimicrobials found in foods including beverages, jams, salads, and cheese, and other antimicrobials are used to prevent mold in bread. Benzoates occur naturally in cranberries. According to the Agency for Toxic Substances & Disease Registry, nitrates and nitrites have been linked to breathing, blood pressure and reproductive problems as well as cancer.

Antioxidants

• Antioxidants are preservatives that impede the chemical breakdown of food that takes place due to contact with the air. Oil is very susceptible to this kind of oxidation. Some food contains enzymes that start to turn the food as soon as it is cut. You can see this breakdown in apples and potatoes when they turn brown immediately. Citric acid and ascorbic acid (vitamin C) can prevent this oxidation.

Sulfites

• Sulfites like sulfur dioxide are chemical preservatives added to many fruits and fruit products to keep the food fresh. According to the U.S. Food and Drug Administration, for those who are allergic to sulfites, exposure can cause symptoms from headache and stomach cramps to anaphylactic shock and even death for those with asthma. Sulfites are common in foods such as dried fruits and vegetables, balsamic vinegar, lemon juice and wine. They work by interfering with the cell's energy and inhibiting metabolic pathways.