Related Terms

• 2,4-hexadienoic acid, antimicrobial agents, calcium sorbate, food additives, fungistatic agents, potassium sorbate, preservatives, rowan, sodium sorbate.

Background

• Sorbic acid is a natural, organic preservative frequently used to maintain the freshness of a variety of human foods, drugs, and cosmetic products. Potassium sorbate and sorbic acid possess antifungal, and to a lesser extent antibacterial, properties.

• Sorbic acid reacts with other chemical compounds to make what are known as derivatives. Such derivatives include calcium sorbate, potassium sorbate, and sodium sorbate.

• Sorbic acid was first made by the hydrolysis of oil distilled from unripe mountain-ash berries in 1859. In 1900, the first synthesis or sorbic acid was performed by Doebner. Sorbic acid was made from crotonaldehyde and malonic acid in pyridine. The antifungal effects of sorbic acid were discovered in the 1940s. Sorbic acid was not used as an additive before that time. Food applications of sorbates expanded rapidly after the issuance of the original patents in 1945.

• In the United States, sorbic acid is primarily used in a wide range of food and feed products and to a lesser in certain cosmetics, pharmaceuticals and tobacco products. Sorbic acid is used as a preservative at concentrations of up to 0.2%.

• Sorbic acid is tightly regulated as a food additive in Australia, and many natural health food stores do not sell products that have been treated with this chemical compound. However, the ban is usually not extended to products treated with derivatives of sorbic acid.

Technique

• Sorbic acid is commonly used in the United States to preserve products such as wines, cheeses, baked goods, fresh fruits and vegetables, and refrigerated meat. Sorbic acid is also added to pharmaceuticals and cosmetic products.

• Sorbic acid may be used in wines to prevent secondary fermentation of sugar and recontamination by yeast. The most common methods of application for dairy products includes dipping or spraying with potassium sorbate solutions for natural cheeses, and direct addition to processed cheeses. Sorbates are commonly used to extend the life of fish and shellfish. They inhibit the development of yeast and mold in the fish product. Sorbates are applied as a fungistat for prunes, pickles, relishes, maraschino cherries, olives, and figs and are used to extend the shelf life of prepared salads. Sorbates also preserve meat and poultry. For example, country-cured hams sprayed with sorbate solution result in no mold growth for 30 days.

• Individual countries create laws regarding the use of sorbic acid in food products. In the United States, the Food and Drug Administration enforces laws regarding acceptable levels of sorbic acid in various foods, drugs, and other products.

Theory/Evidence

• Sorbic acid is a white crystalline solid. It has a melting point of 134.5°C, a boiling point of 228°C and a pKa of 4.76.The chemistry of sorbic acid is determined by the carboxyl group and the conjugate double bonds.

• Sorbic acid can be inactivated by oxidation and to some extent by nonionic surfactants and plastics. The activity of the sorbates may be reduced by increases in pH. Sorbic acids are relatively ineffective above a pH of 6.5.

• Sorbic acid and its mineral salts, such as sodium sorbate, potassium sorbate and calcium sorbate, are antimicrobial agents often used as preservatives in food and drinks to prevent the growth of mold, yeast, and fungi. In general, the salts are preferred over the acid form because they are more soluble in water.

• The un-dissociated sorbic acid molecule is responsible for the inhibitory effect of this compound. The exact mechanism of this inhibitory effect is unknown. Most scientists propose that it is not possible for food cells to develop resistance to sorbic acid. However, the break down time of sorbic acid is not known; the unknown mechanisms, expiration date, and effects of sorbic acid and its derivatives have caused concern among some people. These issues are under investigation by the scientific community.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

• Sorbic acid may be an irritant. An allergic reaction to sorbic acid may occur if it is inhaled, ingested or in contact with the skin. Inhalation or ingestion of pure sorbic acid should be considered a medical emergency.

• Individuals who are frequently exposed to sorbic acid may become hypersensitive.

Author Information

• This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

1. Australia New Zealand Food Standards.30 May 2006. www.foodstandard.gov.au

2. Beasley MW. Sorbic acid. In: Rowe RC, et al., eds. Handbook of pharmaceutical excipients. 4th ed. London and Chicago: The Pharmaceutical Press and the American Pharmaceutical Association, 2003: 588-90.

3. Fisher A. Sorbic acid: a cause of immediate nonallergic facial erythema. An update. Cutis. 1998 Jan;61(1):17. View Abstract

4. Food and Drug Administration.8 June 2006. www.fda.gov

5. Giordano-Labadie F, Pech-Ormieres C, Bazex J. Systemic contact dermatitis from sorbic acid. Contact Dermatitis. 1996 Jan;34(1):61-2. View Abstract

6. Patrizi A, Orlandi C, Vincenzi C, et al. Allergic contact dermatitis caused by sorbic acid: rare occurrence. Am J Contact Dermat. 1999 Mar;10(1):52. View Abstract

7. Perez-Prior MT, Manso JA, Garcia-Santos Mdel P, et al. Alkylating potential of potassium sorbate. J Agric Food Chem. 2005 Dec 28;53(26):10244-7. View Abstract

8. Soschin D, Leyden JJ. Sorbic acid-induced erythema and edema. J Am Acad Dermatol 1986; 14: 234-41. View Abstract