Sorbic Acid and Sorbates

Sorbic acid and acetic acid are among the weak organic acid preservatives most commonly used to improve the microbiological stability of foods. They have similar properties, but sorbic acid is a far more potent preservative. Sorbic acid and its salts are mainly synthesized in the laboratory but they exist in many fruits. In fact, the name"sorbic acid" is derived from Sorbus aucuparia and this compound was first isolated from the berries of this plant in 1859. Its microbiological properties were discovered much later and this substance has become a common preservative for a variety of foods and pharmaceutical products in many countries.8

Sorbic acid and its salts (sorbates) is a broad spectrum antimycotic that is effective against yeast and molds, but are less active against bacteria. Sodium and potassium sorbates have been recognized as safe for use in foods, animal feed and pharmaceutical products under regulations of Food and Drug Administration. Sorbic acid and its sorbates are labelled E200-E203 for use in food. At low concentrations sorbates have been found to be superior to benzoate for preservation of margarine, fish, cheese, bread, and cake because of milder taste, greater effectiveness and boader pH range. The antifungal effect of sorbate is greater at pH less than 5.0. Sorbic acid has little antifungal activity at pH levels higher than 5.6. Although sorbates inhibit the formation of mycotoxins, under certain conditions, at levels below inhibitory they actually may stimulate their production.



The spoilage yeast Saccharomyces cerevisiae is able to degrade sorbic acid to form a volatile hydrocarbon, 1,3-pentadiene. The spoilage yeast Zygosaccharomyces bailii is notorious for its extreme resistance to preservatives and ability to grow in excess of legally-permitted concentrations of preservatives.7 5 Resistance of yeasts to inhibition of sorbates depends on species and strains, sorbate concentration pH, storage temperature and previous exposure of the organism to low levels of sorbates.2 Use of other preservative in cobination with sorbate can broaden or intensify antimicrobial action. Certain lactic acid spoilage bacteria belonging to Lactobacillus and Leuconostoc that grow in soft drinks containing fruit juices are resistent to sorbic acid and sorbates.

Sorbic acid has been implicated in triggering or aggravating urticaria, skin rash notable for pale red, raised, itchy bumps.4 The additives also lower the amount of circulating leptin, the "satiety hormone" made by adipose cells that helps to regulate energy balance by inhibiting hunger, thus reducing satiety effect. Low levels of leptin lead to even more food intake and obesity. Leptin resistance, which later develops during obesity, also favor the developmental process of atherosclerosis.6

References

  1. Introduction to Food Toxicology. Takayuki Shibamoto, Leonard F. Bjeldanes
  2. Natural Food Antimicrobial Systems. A.S. Naidu
  3. Fungal Biotechnology in Agricultural, Food, and Environmental Applications. Dilip K. Arora
  4. Chronic urticaria in adults: state-of-the-art in the new millennium
  5. Health Safety of Soft Drinks: Contents, Containers, and Microorganisms
  6. Antioxidants, inflammation and cardiovascular disease
  7. Extreme resistance to weak-acid preservatives in the spoilage yeast Zygosaccharomyces bailii
  8. Handbook of Food Analysis, Third Edition. Leo M.L. Nollet, Fidel Toldra