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Sorbic acid (Food Preservative), or 2,4-hexadienoic acid, is a natural organic compound used as a food preservative.
Sorbic acid (Food Preservative) has the chemical formula CH3(CH)4CO2H and the structure H3C−CH=CH−CH=CH−C(=O)OH.
Sorbic acid (Food Preservative) is a colourless solid that is slightly soluble in water and sublimes readily.
CAS: 110-44-1
MF: C6H8O2
MW: 112.13
EINECS: 203-768-7
Synonyms
(e,e)-4-hexadienoicacid;(E,E)-Sorbic acid;2,4-Hexadienoicacid,(E,E)-;2e,4e-hexadienoicacid;4-Hexadienoicacid,(E,E)-2;2-PROPENYL ACRYLIC ACID;1,3-Pentadiene-1-carboxylic acid;2,4-HEXANEDIENOIC ACID
Sorbic acid (Food Preservative) was first isolated from the unripe berries of the Sorbus aucuparia (rowan tree), hence its name.
Sorbic acid (Food Preservative), also known as herbal tea acid, 2,4-hexadienoic acid, 2-propenyl acrylic acid, with molecular formula C6H8O2, is a food additive that has inhibitory effects on many fungi such as yeast and mold.
Sorbic acid (Food Preservative) is also used in animal feed, cosmetics, pharmaceuticals, packaging materials and rubber additives.
A Sorbic acid (Food Preservative) having trans-double bonds at positions 2 and 4; a food preservative that can induce cutaneous vasodilation and stinging upon topical application to humans.
Sorbic acid (Food Preservative) is the most thermodynamically stable of the four possible geometri isomers possible, as well as the one with the highest antimicrobial activity.
History
Sorbic acid (Food Preservative) is a white crystalline solid first isolated in 1859 by hydrolysis of the oil distilled from unripened mountain-ash berries.
The name is derived from the scientific term for the rowan tree, Sorbus aucuparia Linne, which is the parent plant of the mountain ash.
Sorbic acid (Food Preservative) was first synthesized in 1900.
Interest in Sorbic acid (Food Preservative) was minimal until independent researchers, E. Mueller of Germany and C.M. Gooding of the United States, discovered its antimicrobial effect in 1939 and 1940, respectively.
Early interest in manufacturing sorbic acid centered around its use as a tung oil replacement when tung oil supplies were curtailed in the United States during World War II. High manufacturing costs prohibited expanded use until its approval as a food preservative in 1953.
Sorbic acid (Food Preservative) is widely used in foods having a pH of 6.5 or below, where control of bacteria, molds, and yeasts is essential for obtaining safe and economical storage life.
Sorbic acid (Food Preservative) Chemical Properties
Melting point: 132-135 °C (lit.)
Boiling point: 228°C
density: 1.2 g/cm3 at 20 °C
vapor pressure: 0.01 mm Hg ( 20 °C)
refractive index: 1.4600 (estimate)
FEMA: 3921 | 2,4-HEXADIENOIC ACID, (E,E)-
Fp: 127 °C
storage temp.: 2-8°C
solubility ethanol: 0.1 g/mL, clear
form: Crystalline Powder
pka: 4.76(at 25℃)
color: White or cream-white
Odor: bland
PH: 3.3 (1.6g/l, H2O, 20°C)
biological source: synthetic
Water Solubility: 1.6 g/L (20 ºC)
Merck: 14,8721
JECFA Number: 1176
BRN: 1741831
Stability: Material saturated with this acid may ignite spontaneously. Incompatible with strong oxidizing agents. May be light sensitive.
Major Application: cleaning products
cosmetics
flavors and fragrances
food and beverages
personal care
Cosmetics Ingredients Functions: PRESERVATIVE
FRAGRANCE
InChI: 1S/C6H8O2/c1-2-3-4-5-6(7)8/h2-5H,1H3,(H,7,8)/b3-2+,5-4+
InChIKey: WSWCOQWTEOXDQX-MQQKCMAXSA-N
LogP: 1.32 at 20℃
CAS DataBase Reference: 110-44-1(CAS DataBase Reference)
NIST Chemistry Reference: Sorbic acid (Food Preservative) (E,E)-(110-44-1)
EPA Substance Registry System: Sorbic acid (Food Preservative) (110-44-1)
Reactions
The chemical reactivity of Sorbic acid (Food Preservative) is determined by the conjugated double bonds and the carboxyl group.
Sorbic acid (Food Preservative) is brominated faster than other olefinic acids.
Reaction with hydrogen chloride gives predominately 5-chloro-3-hexenoic acid.
Reactions with amines at high temperatures under pressure lead to mixtures of dehydro-2-piperidinones.
A yellow crystalline complex is formed from sorbic acid and iron tricarbonyl.
Similar coordination occurs also in the presence of other di- and trivalent metals.
Reduction of the double bonds can produce various hexenoic acid mixtures.
Properties and uses
With a pKa of 4.76, sorbic acid is about as acidic as acetic acid.
Sorbic acid (Food Preservative) and its salts, especially 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, but the active form is the acid.
The optimal pH for the antimicrobial activity is below pH 6.5.
Sorbates are generally used at concentrations of 0.025% to 0.10%.
Adding sorbate salts to food will, however, raise the pH of the food slightly so the pH may need to be adjusted to assure safety.
Sorbic acid (Food Preservative) is found in foods such as various kinds of cheese, bread, muffins, donuts, pies, cookies, protein bars, syrups, lemonades, fruit juices, dried meats, sausages, nuggets, burgers, sandwiches, tacos, pizzas, smoked fish, margarine, sauces, soups, and more.
Uses
Sorbic acid (Food Preservative) is a preservative that is effective against yeasts and molds.
Sorbic acid (Food Preservative) is effective over a broad ph range up to ph 6.5, being ineffective above ph 7.0.
Sorbic acid (Food Preservative) is a white, free-flowing powder which is slightly soluble in water with a solubility of 0.16 g in 100 ml of water at 20°c.
Sorbic acid (Food Preservative)'s solubility in water increases with increasing temperatures, although it is not recommended in foods that are pasteurized because it breaks down at high temperatures.
The salts are potas- sium, calcium, and sodium sorbate.
Sorbic acid (Food Preservative)is used in cheese, jelly, bever- ages, syrup, and pickles.
typical usage levels range from 0.05 to 0.10%.
Sorbic acid (Food Preservative) is a broad-spectrum, non-toxic preservative against molds and yeasts with moderate sensitizing potential in leave-on cosmetics.
Sorbic acid (Food Preservative) is used in concentrations of 0.1 to 0.3 percent, and its activity is dependent on the formulation’s pH.
Sorbic acid (Food Preservative) is used as a replacement for glycerin in emulsions, ointments, and various cosmetic creams.
Sorbic acid (Food Preservative) is obtained from the berries of the tree commonly known as mountain ash and rowan, and can also be produced synthetically.
Sorbic acid (Food Preservative) can cause irritation.
Sorbic acid (Food Preservative)is an naturally occurring organic compound first isolated from unripe berries.
Sorbic acid (Food Preservative) has been used as a food preservative and as an inhibitor of Clostridium Botulinum bacteria in meat products in order to reduce the amount of nitrites which produce carcinogenic nitroamines.
Mold and yeast inhibitor.
Fungistatic agent for foods, especially cheeses.
To improve the characteristics of drying oils.
In alkyd type coatings to improve gloss.
To improve milling characteristics of cold rubber.
Biotechnological Production
Today, Sorbic acid (Food Preservative) is produced solely by chemical synthesis.
However, fermentation and chemical synthesis might be combined to develop a new production route for Sorbic acid (Food Preservative).
In a first step, glucose would be converted to triacetic acid lactone by fermentation.
Sorbic acid (Food Preservative) has been shown that triacetic acid lactone can be produced by genetically modified E. coli and S. cerevisiae strains.
After a separation from the fermentation broth, triacetic acid lactone would be transformed into butyl sorbate in a multistage catalyst system (catalysis-hydrogenation and solid acid catalysis).
Then, butyl sorbate would be purified and hydrolyzed to sorbic acid.
Different scenarios are analyzed to evaluate the economic feasibility of such a production process.
Synthesis
Crotonaldehyde and malonic acid condensation, decarboxylation to get sorbic acid, crotonaldehyde and malonic acid with pyridine as a solvent at 90-100 reaction for 4-5 hours, and then add dilute sulfuric acid so that the solution is weakly acidic (pH value of about 4-5) freezing, filtration, crystallization to get crude Sorbic acid (Food Preservative).
Production
The traditional route to Sorbic acid (Food Preservative) involves condensation of malonic acid and crotonaldehyde.
Sorbic acid (Food Preservative) can also be prepared from isomeric hexadienoic acids, which are available via a nickel-catalyzed reaction of allyl chloride, acetylene, and carbon monoxide.
The route used commercially, however, is from crotonaldehyde and ketene.
An estimated 30,000 tons are produced annually.
