Unless you grow all your food in your own garden and prepare all your meals from scratch, it's almost impossible to eat food without preservatives added by manufacturers during processing. Without such preservatives, food safety problems would get out of hand, to say nothing of the grocery bills. Bread would get moldy, and salad oil would go rancid before it's used up.
Food law says preservatives must be listed by their common or usual names on ingredient labels of all foods that contain them--which is most processed food. You'll see calcium propionate on most bread labels, disodium EDTA on canned kidney beans, and BHA on shortening, just to name a few. Even snack foods--dried fruit, potato chips, and trail mix--contain sulfur-based preservatives.
Manufacturers add preservatives mostly to prevent spoilage during the time it takes to transport foods over long distances to stores and then to our kitchens.
It's not unusual for sourdough bread manufactured in California to be eaten in Maine or for olive oil manufactured in Spain to be used on a California salad. Rapid transport systems and ideal storage conditions help keep foods fresh and nutritionally stable. But breads, cooking oils, and other foods, including the complex, high-quality convenience products consumers and food services have come to expect, usually need more help.
Preservatives serve as either antimicrobials or antioxidants--or both. As antimicrobials, they prevent the growth of molds, yeasts, and bacteria. As antioxidants, they keep foods from becoming rancid, browning, or developing black spots. Rancid foods may not make you sick, but they smell and taste bad. Antioxidants suppress the reaction that occurs when food combines with oxygen in the presence of light, heat, and some metals. Antioxidants also minimize the damage to some essential amino acids--the building stock of proteins--and the loss of some vitamins. (See "Why Better Diet Means Better Health," CR, June 1993.)
Safety Questions. Many preservatives are regulated under the food additives amendment, added to the federal Food, Drug and Cosmetic Act in 1958. The amendment strengthened the law to ensure safety of all new ingredients that manufacturers add to foods. Under these rules, a food manufacturer must get Food and Drug Administration (FDA) approval before using a new preservative, or before using a previously approved preservative in a new way or in a different amount. In its petition for approval, the manufacturer must …