rowan tree berries

Sorbic acid is a food preservative which originated from rowan tree berries.

Sorbic Acid


What is Sorbic Acid?

Sorbic acid is a food preservative, primarily used to inhibit mold growth. It is an organic compound, with naturally strong antimicrobial capabilities. This additive is one of the most popular food preservatives, acting as a protectant to many food varieties from yeast and mold spoilage.

It is most often found in baked goods, cheeses, wines, fresh produce and refrigerated meat. Due to it’s effectiveness, sorbic acid is used for cosmetics as well.

Sorbic acid does not create carcinogenic byproducts, as some preservatives such as nitrates do. It also has no noticeable taste or odor when used in baked goods. The salts of sorbic acid – sodium sorbate, calcium sorbate, and potassium sorbate – are more soluble in water than the original form. Potassium sorbate has the highest solubility and is the most commonly used form in the food industry.1

Origin

Sorbic acid was first discovered in 1859 from unripe berries of the rowan tree (Sorbus aucuparia), which is where the name originated. However, it was not until the late 1930s that its antimicrobial properties were revealed. It was discovered first in Germany by E. Muller and then a few months later by C. S. Gooding in the U.S.

By the 1950s, it was being produced industrially. The early uses of the sorbic acid salts were to defend meat against the botulism-causing bacteria Clostridium botulinum. Its popularity grew for its organoleptic neutrality and over the last 30 years has become one of the most-used preservatives.2

Commercial Production

Sorbic acid is produced synthetically for commercial use. The main method is creating a condensation reaction of ketene and crotonaldehyde. It is purified with a treatment of sodium hydroxide, hydrochloric acid and activated carbon. For food uses and increased solubility in water, it is granulated by extrusion and pelletization.3

Function

Sorbic acid is a carboxylic acid, virtually odorless and tasteless when used in food processing. It is available in powder, granule and solution form or it can be encapsulated. When adding any sorbate form to food products, methods range from treating packaging materials, dipping and spraying foods, or dusting with a dry form.4 Sorbic Acid may also be blended with dry ingredients first, such as flour, salt, or cornstarch, before being added into a formula.

Encapsulation allows sorbic acid to be added directly to the dough, preserving the product from the inside out without killing baker’s yeast. The coating of encapsulates are mainly comprised of lipids (fats), and melt away at temperatures above 145oF. This releases the sorbic acid after yeast kill temperatures (140oF) in the oven. Sometimes, encapsulated sorbic acid is used in conjunction with calcium propionate. The combined use of these preservatives can inhibit a broad range of different spoilage microorganisms, extending mold-free shelf life. Encapsulated sorbic acid can also be used in frozen products without affecting its antimicrobial properties.

The advantage of sorbic acid over other food preservatives, such as propionic or benzoic acid, is that it does not impair the final product’s flavor. This is because  less sorbic acid is needed by weight over other preservatives. Sorbic acid, as well as its salts, functions best in products with pH between 4.0 and  7.0.

Sorbic acid has a water solubility of around 0.16g/100 ml, and increases with temperature.5 Its solubility is higher in ethanol, but slows with added sugar. Sorbic acid inhibits yeasts strains differently, as some strains are more tolerant to its effects than others.6

FDA

Sorbic acid and its salts are classified as GRAS by the FDA, as a chemical preservative. Production and use guidelines fall under standard procedures for food additives.7

References

  1. Lück, E. “Food Applications of Sorbic Acid and Its Salts.” Food Additives and Contaminants 7.5 (1990): 711-15.
  2. 2.Lück, Erich, and Martin Jager. Antimicrobial Food Additives: Characteristics. Uses. Effects. Berlin: Springer, 1997.
  3. Naidu, A. S. “Sorbic Acid.” Natural Food Antimicrobial Systems. Boca Raton, FL: CRC, 2000. N. pag.
  4. Ohtsuki, Takashi, Kyoko Sato, Naoki Sugimoto, Hiroshi Akiyama, and Yoko Kawamura. “Absolute Quantitative Analysis for Sorbic Acid in Processed Foods Using Proton Nuclear Magnetic Resonance Spectroscopy.”Analytica Chimica Acta 734 (2012): 54-61.
  5. Tzatzarakis, M., E. Charvalos, A. Tsatsakis, and G. Petrikkos. “Controlled Release of Water-soluble Polymeric Complexes of Sorbic Acid with Antifungal Activities.” Applied Microbiology and Biotechnology 57.5-6 (2001): 770-75.
  6. Neves, L., M.e. Pampulha, and M.c. Loureiro-Dias. “Resistance of Food Spoilage Yeasts to Sorbic Acid.” Letters in Applied Microbiology Lett Appl Microbiol 19.1 (1994): 8-11.
  7. “CFR – Code of Federal Regulations Title 21.” Accessdata.fda.gov. www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm?fr=133.123. Accessed  14 Apr. 2017