Calcium sorbate is a calcium salt of sorbic acid. It is a polyunsaturated fatty acid salt. It appears as white crystalline powder. Due to its antimicrobial properties, calcium sorbate is used commonly as preservative in food and cosmetic products. It is generally non-toxic and safe for exposure. Like other sorbate salts, the primary component of calcium sorbate, sorbic acid, is naturally occurring and can be isolated from Rowan berries.
Calcium hydroxide is added to sorbic acid in a reaction of neutralisation. Stoichiometric amounts of calcium hydroxide and sorbic acid are measured and added in precision. To increase the yield of calcium sorbate, sorbic acid is normally added in excess of about 1.05 to 2 times the stoichiometric amount. Other acids like malic acid and lactic acid may be added to lower the pH of the mixture such that an optimal pH is achieved.
The reaction mixture is heated to about 80°C and carried out under pressurised condition. The resulting mixture is then crystallised to obtain solid calcium sorbate. Since solid calcium sorbate is sparingly soluble in water, it is usually coated with wetting agent before packaged for commercial purposes.
Calcium sorbate is used in the food industry as an antioxidant and preservative in food products as it can retard microbial growth and mould growth.
Due to its antimicrobial property, it is also used in the packaging of pharmaceutical products like drugs.