An ancient practice designed to prevent spoilage, among the first food preservation practices were the salting of meat and fish, adding sugar in canned foods and pickling vegetables. Today, preservatives continue this important role.
Food preservatives play a vital role in preventing deterioration of food, protecting against spoilage from mold, yeast, life-threatening botulism and other organisms that can cause food poisoning. By extension, preservatives reduce food cost, improve convenience, lengthen shelf life and reduce food waste.
Functions, Names and Labeling
There are two modes of preservation: physical and chemical. Physical preservation refers to processes such as refrigeration or drying. Chemical preservation is adding ingredients to a food for the purpose of preventing potential damage from oxidation, rancidity, microbial growth or other undesirable changes — and is considered a “direct additive.”
The U.S. Food and Drug Administration classifies both natural preservatives (for example, from lemon juice, salt and sugar) and artificial preservatives as “chemical preservatives.” While many common preservatives occur naturally, manufacturers often use synthetic versions of these chemicals. Artificial preservatives can be divided into three major groups:
Antimicrobial agents destroy bacteria or inhibit the growth of mold on foods:
- Benzoates – the salts of benzoic acid
- Sorbates – sorbic acid and its three mineral salts, potassium sorbate, calcium sorbate and sodium sorbate
- Propionates – the salts of propionic acid
- Nitrites – the salts of nitrous acid
Antioxidants inhibit oxidation:
- Sulfites – a group of compounds containing charged molecules of sulfur compounded with oxygen, including sodium sulfite, sodium bisulfite, sodium metabisulfite, potassium bisulfite and potassium metabisulfite
- Vitamin E (tocopherol) – a fat-soluble vitamin
- Vitamin C (ascorbic acid) – a water-soluble vitamin and its salts, sodium ascorbate, calcium ascorbate and potassium ascorbate
- Butylated hydroxyanisole (BHA) – a waxy solid used to preserve butter, lard, meats and other foods
- Butylated hydroxytoluene (BHT) – similar in structure and function to BHA, but in powder form
Chelating agents bind metal ions in certain foods to prevent oxidation:
- Disodium ethylenediaminetetraacetic acid (EDTA) – used in food processing to bind manganese, cobalt, iron or copper ions
- Polyphosphates – used as anti-browning agents in dips and washes for peeled fruits and vegetables
- Citric acid – found naturally in citrus fruits
All preservatives added to food products must be declared on the ingredient list on the food label using common names of ingredients. When no such name exists, synthetic forms can be listed. For example, synthetic vitamin B9 can be listed as “folic acid.” Preservative ingredients must either be identified as a preservative or the specific function must be given, such as “sorbic acid (to retain freshness).”
The FDA has jurisdiction over all preservatives, with the Food Safety and Inspection Service sharing responsibility for the safety of food additives used in meat, poultry and egg products. The FDA mandates that preservatives not be used in such a way as to conceal damage or inferiority, make the food appear better than it is or adversely affect the nutritive value of the food. Food additives approved for use as preservatives are listed in the U.S. Code of Federal Regulations.
According to the regulatory authorities, preservatives are generally recognized as safe, or GRAS, in the quantities in which they are allowed in individual food products. “Safe” for food additives is defined to mean “a reasonable certainty in the minds of competent scientists that the substance is not harmful under the intended conditions of use.” Still, there are some preservatives of concern.
Sodium nitrite/nitrate used in processed meats is an example of compounds that may increase the potential of these foods to cause cancer. Studies have linked eating large amounts of processed meats with an increased risk of colorectal cancer.
Sodium benzoate and sulfites appear to be safe for most people, but may cause adverse reactions in others. A 2007 study published in The Lancet suggests sodium benzoate and artificial food colorings may exacerbate hyperactivity in young children.
Although butylated hydroxyanisole, or BHA, is listed by the National Toxicology Program as “reasonably anticipated to be a human carcinogen,” the FDA considers it a GRAS substance in minute quantities. Meanwhile, butylated hydroxytoulene, or BHT, has been banned in some countries but has not been shown conclusively to be carcinogenic.
To be clear, a diet awash with processed foods may contain excessive preservatives — both artificial and natural (think salt and sugar) — and should be limited. But preservatives within the context of an overall healthful diet help safeguard food and protect consumer health, neither of which are reasonable tradeoffs.
“Removing preservatives compromises food safety, and there is no good scientific reason to avoid them,” says Robert Brackett, PhD, director of the Institute for Food Safety and Health. He used nitrates as an example: “The
risk of getting botulism from processed meats far outweighs the risk of the preservative especially when consumed in moderation.”
Nonetheless, emerging technological innovations aimed at replacing traditional preservatives are in the works. Development of technologies such as high-pressure processing and ultrasonic preprocessing with pulsed light are promising — and may yield additional benefits such as reduced water usage, energy efficiency and improved food quality.