Preservatives are substances that prolong the shelf life of food by slowing down their natural breakdown, mainly by altering the action of bacteria and other microorganisms. People commonly classify preservatives as "natural" or "artificial," depending on the method of production, and as "antimicrobial," "antioxidant" or "chelating" agents, depending on the primary mode of action. In recent years, preservatives have earned a particularly unsavory reputation, especially within the ever-widening health-conscious circle.
Natural vs. Artificial
Salt, sugar, vinegar and alcohol are good examples of naturally-occurring preservatives. For centuries, people have resorted to salting, pickling and making jams and jellies to extend the life of their fresh meats and produce. Other natural preservatives, such as ascorbic and citric acid, slow the discoloration of fruits and vegetables by retarding enzymatic action. Artificial substances are, as the name implies, man-made, and constitute the vast majority of food additives and preservatives today. They have long been a point of contention among food manufacturers, consumers and nutritionists.
Antimicrobial, Antioxidant and Chelating Agents
Preservatives vary in their primary method of keeping food safe and palatable. Antimicrobial agents, such as benzoates, sorbates and nitrites, inhibit the growth of bacteria and fungi in food and beverages. Antioxidants, such as sulfites, vitamin C, vitamin E and BHT prevent the oxidation of beer, wine, fresh and dried produce and fatty food. Chelating agents such as EDTA, polyphosphates and citric acid deactivate enzymes that cause rancidity in food by sequestering metal ions such as iron and copper.
It is a common, though largely unfounded, notion that all artificial food additives have adverse health effects. Although it is true that some preservatives such as benzoates and sulfites can cause anything from allergies to cancer and even brain damage when consumed in excess amounts, the FDA and other international food regulatory organizations carefully monitors their use. In truth, the human body is just as likely to have unfavorable reactions to flavoring or coloring agents as to preservatives.
In response to consumers jumping on the healthy-living bandwagon, food manufacturers have adapted by plastering their products with labels claiming that they use no artificial preservatives. The fact remains, however, that as long as customers demand that their food reach their pantries—as well as stomachs—in prime condition at a later time and date, preservatives will be used.
Even healthy-living advocates who insist on touting diets consisting purely of fresh produce as preservative-free have no real assurance, as pesticides and preservative coatings are often necessary to keep fruits and vegetables fresh on supermarket shelves. Growing your own food or buying exclusively from organic farmers remains the only true way of achieving a 100% preservative-free diet.