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SORBIC ACID
Sorbic acid, or 2,4-hexadienoic acid, is a natural organic compound used as a food preservative. It has the chemical formula CH3(CH)4CO2H. It is a colourless solid that is slightly soluble in water and sublimes readily. It was first isolated from the unripe berries of the Sorbus aucuparia (rowan tree), hence its name.
SORBIC ACID
CAS No.: 110-44-1
EC No.: 203-768-7
SYNONYMS
sorbic acid; 110-44-1; 2,4-Hexadienoic acid; (2E,4E)-hexa-2,4-dienoic acid; 2E,4E-Hexadienoic acid; Hexa-2,4-dienoic acid; Panosorb; Sorbistat; 2,4-Hexadienoic acid, (2E,4E)-; 2-Propenylacrylic acid; trans,trans-Sorbic acid; Hexadienoic acid; E,E)-2,4-Hexadienoic acid; alpha-trans-gamma-trans-Sorbic acid; Preservastat; (E,E)-Sorbic acid; trans,trans-2,4-Hexadienoic acid; 2,4-Hexadienoic acid, (E,E)-; Crotylidene acetic acid; Kyselina sorbova; Acetic acid, crotylidene-; Caswell No. 801; Sorbic Acid [USAN]; Acidum sorbicum; Acetic acid, (2-butenylidene)-; Kyselina sorbova [Czech]; trans-trans-2,4-Hexadienoic acid; (E,E)-1,3-pentadiene-1-carboxylic acid; (2E,4E)-2,4-Hexadienoic acid; Hexadienoic acid, (E,E); (2-Butenylidene)acetic acid; C6:2n-2,4; Sorbic acid (NF); Sorbic acid [NF]; UNII-X045WJ989B; CCRIS 5748; HSDB 590; 1,3-Pentadiene-1-carboxylic acid; 1,3-Pentadiene-1-carboxylic acid, (E,E)-; E 200; EINECS 203-768-7; MFCD00002703; 5309-56-8; Kyselina 1,3-pentadien-1-karboxylova; EPA Pesticide Chemical Code 075901; (2-butenylidene) acetic acid; AI3-14851; CHEBI:38358; Kyselina 1,3-pentadien-1-karboxylova [Czech]; (E,E)-Sorbic acid; Sorbic acid; X045WJ989B; 22500-92-1; NCGC00091737-01; DSSTox_CID_1277; DSSTox_RID_76053; DSSTox_GSID_21277; Hexadienic acid; 2,4-Hexadienoic acid, 99%; (2E,4E)hexa-2,4-dienoic acid; CAS-110-44-1; Sorbic acid solution; (2E)-2,4-Hexadienoic acid; Sorbic acid, (E,E)-; Sorbinsaeure; Sorbinsaure; NSC49103; E-sorbic acid; trans,trans-SA; sorbic acid group; Sorbic Acid FCC; Hexa-2,4-dienoic acid, (E,E)-; 2,4-Hexadiensaeure; NSC 35405; NSC 49103; NSC 50268; Crotylidene-Acetic acid; EC 203-768-7; SCHEMBL1647; Sorbic acid 110-44-1; Sorbic acid, >=99.0%; 91751-55-2; MLS002152937; (2-butenylidene)-Acetic acid; (E,E)-SA; CHEMBL250212; (e,e)-hexa-2,4-dienoic acid; DTXSID3021277; Sorbic acid, analytical standard; CHEBI:35962; FEMA 3921; HMS3039E13; Sorbic acid, potassium salt (van); HY-N0626; STR09707; ZINC1558385; Tox21_111164; Tox21_201719; Tox21_300182; 2,4-SA; LMFA01030100; LS-504; s4983; SBB060282; (2E,4E)-2,4-Hexadienoic acid #; 2, 4-Hexadienoic acid potassium salt; AKOS000119456; CCG-266056; NE10215; 2,4-Hexadienoic acid, (trans,trans)-; 2,4-Hexadienoic acid, >=99%, FCC; alpha.-trans-.gamma.-trans-Sorbic acid; NCGC00091737-02; NCGC00091737-03; NCGC00091737-05; NCGC00253957-01; NCGC00259268-01; E200; P891; SMR001224532; Sorbic acid, tested according to Ph.Eur.; Sorbic acid, SAJ first grade, >=98.5%; CS-0009618; S0053; Sorbic acid 1000 microg/mL in Acetonitrile; Sorbic acid, Vetec(TM) reagent grade, 98%; ST51046499; Sorbic acid, for synthesis, 99.0-101.0%; alpha-trans-Laquo gammaRaquo -trans-sorbic acid; D05892; Hexadienoic acid1,3-pentadiene-1-carboxylic acid; A829400; AN-651/40229308; Q407131; J-002425; J-524281; 2,4-Hexadienoic acid, (E,E)-; 2,4-Hexadienoic acid; F8886-8255; Sorbic acid, European Pharmacopoeia (EP) Reference Standard; Sorbic acid, United States Pharmacopeia (USP) Reference Standard; Sorbic acid, Pharmaceutical Secondary Standard; Certified Reference Material
SORBIC ACID
Sorbic acid, an unsaturated six-carbon fatty acid, is a naturally occurring preservative that is used less in food compared to its potassium salt – potassium sorbate (E202) due to the slight solubility in water. This ingredient can be used in low water content food such as baked goods, cheese, dried fruits, meat and fatty media.
It is generally used to inhibit the growth of molds (also mycotoxin-forming molds), yeast and some bacteria. The European food additive number for it is E200.
Sorbic acid appears as white powder or crystals. Its melting point is 134.5°C. Sorbic acid is slightly acidic and astringent taste with a faint odor.
It can be naturally found in berries species, such as mountain ash, rowan and magnolia vine.
Sorbic acid is a hexadienoic acid with double bonds at C-2 and C-4; it has four geometrical isomers, of which the trans,trans-form is naturally occurring. It is a hexadienoic acid, a polyunsaturated fatty acid, a medium-chain fatty acid and an alpha, beta-unsaturated monocarboxylic acid. It is a conjugate acid of a sorbate.
Sorbic acid has become one of the most commonly used food preservatives in the world. It’s highly effective at inhibiting the growth of mold, which can spoil food and spread fatal diseases.
Preservatives have received a negative connotation in the cosmetic and skin care industry because of claims that preservatives are hazardous to health. This is why many organic and natural beauty brands often include “preservative free” claims on product labels. However, the use of preservatives is necessary in most products to prevent microbial contamination, as well as to prevent degradation by environmental factors such as heat, light, and air.
Most cosmetics have a high potential for microbial contamination and growth, especially creams and lotions that are packed in jars, opened frequently, and applied to the skin with the fingers. Another cause of inadvertent contamination is the use of makeup brushes around the eyes or other parts of the face that touch the skin and the cosmetic repeatedly. Each use increases the chance for contamination. Furthermore, contamination may occur if the consumer leaves a product container open for an extended period of time.
Storage conditions are also a major cause of contamination in cosmetics and personal care products. Since the majority of products are stored at room temperature, the warm temperature can stimulate the growth of microorganisms. Furthermore, the ingredients used in cosmetic formulations, such as water, oils, peptides, and a variety of carbohydrates, create the perfect environment for microorganism growth. Microbial contamination can lead to significant health problems, from skin irritation to infections.
All of these factors mean that a strong yet non-irritating preservative must be added to the formulation of a product to prevent contamination and degradation. Sorbic acid fits both of these criteria.
Because of their physiological inertness, their effectiveness even in the weakly acid pH range and their neutral taste, sorbic acid and its salts have become the leading preservatives in the food sector throughout the world over the past 30 years. The most commonly used products are sorbic acid itself (E200) and potassium sorbate (E202). In many countries sodium sorbate (E201) and calcium sorbate (E203) are also permitted. Sorbic acid is sparingly soluble in water, sodium sorbate has better solubility, and potassium sorbate is very freely soluble and can be used to produce 50% stock solutions. The soluble sorbates are preferred when it is desired to use the preservative in liquid form, or when aqueous systems are to be preserved.
Sodium sorbate in solid form is unstable and very rapidly undergoes oxidation on exposure to atmospheric oxygen. It is therefore not produced on the industrial scale. Aqueous solutions of sodium sorbate remain stable for some time.
Calcium sorbate is used in the manufacture of fungistatic wrappers because it is highly stable to oxidation, but this use is very limited. Sorbic acid and sorbates can be directly added into the product. The products can be dipped or sprayed with aqueous solutions of sorbates. Dusting of food with dry sorbic acid is also possible but less recommended because sorbic acid irritates the skin and mucous membranes. Sorbic acid and particularly calcium sorbate can be used as active substances in fungistatic wrappers.
Sorbic acid is weak acid preservative and is normally used in skincare in its derivative form, potassium sorbate.
Potassium sorbate, not being a broad spectrum preservative for cosmetics and skincare use, should be combined with other preservatives. For example, potassium sorbate and sodium benzoate are often combined in food additives that are generally employed for the prevention of food spoilage originating from bacteria, molds or yeasts.
When Sodium benzoate is used as a preservative, the pH of the final formulation may have to be lowered to facilitate the release of the free benzoic acid for useful activity. Potassium sorbate is often combined with Sodium Benzoate in low pH products to provide a synergistic preservative effect against yeast and mold.
Sorbic acid which is found naturally in some berries has become one of the most commonly used food preservatives in the world. It’s highly effective at inhibiting the growth of mold, which can spoil food and spread fatal diseases. Sorbic acid is weak acid preservative and is normally used in skincare in its derivative form, potassium sorbate. Potassium sorbate, not being a broad spectrum preservative for cosmetics and skincare use is often combined with potassium sorbate. Potassium sorbate and sodium benzoate are frequently combined in food additives and cosmetics employed for the prevention of spoilage originating from bacteria, molds or yeasts. Sorbic acid is considered to be a low-risk ingredient for skincare use and safe to use in skincare.
Sorbic acid is a naturally occurring compound that’s become the most commonly used food preservative in the world, and it makes the global food chain possible. It’s highly effective at inhibiting the growth of mold, which can spoil food and spread fatal diseases. For example, when sorbic acid is sprayed on the exterior of a country ham, there won’t be any mold growth for 30 days. This allows for food to be shipped and stored all over the globe.
Sorbic acid is a preferred preservative compared to nitrates, which can form carcinogenic byproducts. It’s applied to food by either spraying or dipping the food with a solution of sorbic acid and water.
HISTORY
Sorbic acid was isolated in 1859 by distillation of rowanberry oil by A. W. von Hofmann. This affords parasorbic acid, the lactone of sorbic acid, which he converted to sorbic acid by hydrolysis. Its antimicrobial activities were discovered in the late 1930s and 1940s, and sorbic acid became commercially available in the late 1940s and 1950s. Beginning in the 1980s, sorbic acid and its salts were used as inhibitors of Clostridium botulinum in meat products to replace the use of nitrites, which can produce carcinogenic nitrosamines.
How is Sorbic Acid made?
It is commercially synthesized from the condensation between ketene and crotonaldehyde instead of extracted from berries. The manufacturing process is described in the first three steps of production of potassium sorbate.
How Sorbic Acid works as a Preservative?
The bacteriostatic or bactericidal mechanism of sorbic acid are the same as that of potassium sorbate. When added to water, potassium sorbate dissociates into sorbic acid and potassium ions. It is the sorbic acid that is active as an antimicrobial preservative.
Like benzoic acid, sorbic acid is a lipid-soluble weak acid that:
• enters into the cell of microbial through the cell membrane
• then accumulates and finally influences the internal PH of microbial
• eventually disrupts its transport functions and metabolic activity
• result in the death of the microbial
As a Food Preservative:
Sorbic acid is most commonly found in foods, animal feeds, pharmaceutical drugs, and cosmetics.
When it comes to human foods, sorbic acid is most commonly used in:
• wines
• cheeses
• baked goods
• fresh produce
• refrigerated meat and shellfish
Sorbic acid is used to preserve meats because of its natural antibiotic capabilities. In fact, its earliest use was against one of the deadliest toxins known to mankind, the bacteria Clostridium botulinum, which can cause botulism. Its use saved countless lives by preventing bacterial growth while allowing meats to be transported and stored safely.
Because of its anti-fungal properties, sorbic acid is also used in canned goods, including pickles, prunes, maraschino cherries, figs, and prepared salads.
PRODUCTION
The traditional route to sorbic acid involves condensation of malonic acid and trans-butenal. It 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.
SOLUBILITY
In water:
Slightly soluble in water (solubility 0.16 g/100 mL at 20 °C) so it is not suitable to use it in food with much water content. Generally, it is made into salts form, potassium sorbate, which is the commonly utilized form.
In organic solvent:
Soluble in ethanol, ether, propylene glycol, peanut oil, glycerin and glacial acetic acid.
PH
The antimicrobial activity of sorbic acid generates when it is in the form of a molecule, the condition of undissociated.
The PKa of sorbic acid is 4.76. That’s to say, its inhibitory activity rises as pH value (below 4.76) decreases as the percentage of the undissociated sorbic acid goes up, this leads to the enhanced antimicrobial activity.
The optimal pH for the antimicrobial activity is from 3.0 to 6.5.
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. It may also be blended with dry ingredients first, such as flour, salt, or cornstarch, before being added into a formula.
Encapsulation allows this 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, the encapsulated form 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 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. 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
PROPERTIES AND USES
With a pKa of 4.76, sorbic acid is about as acidic as acetic acid.
Sorbic acid is an important commercial chemical used as a preservative and antimicrobial agent that is added to foods and animal feeds, cosmetics, pharmaceuticals and tobacco. It is also added to the packaging material for food products.
Sorbic acid and its 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, 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 is found in foods such as cheeses and breads.
The E numbers are:
E200 Sorbic acid
E201 Sodium sorbate
E202 Potassium sorbate
E203 Calcium sorbate
Some molds (notably some Trichoderma and Penicillium strains) and yeasts are able to detoxify sorbates by decarboxylation, producing trans-1,3-pentadiene. The pentadiene manifests as a typical odor of kerosene or petroleum. Other detoxification reactions include reduction to 4-hexenol and 4-hexenoic acid.
Sorbic acid can also be used as an additive for cold rubber, and as an intermediate in the manufacture of some plasticizers and lubricants.
What are the Uses of Sorbic Acid?
Sorbic acid and potassium sorbate have become the primary preservatives in food application due to its good antimicrobial activity & effectiveness in the weak acid pH range and their safety over benzoic acid and sodium benzoate.
Mostly, it protects food from yeast and mold spoilage and commonly added with usage from 0.025% to 0.10%.
Sodium sorbate and Calcium sorbate:
Another two sorbates, sodium sorbate and calcium sorbate which were also used as food additives in Europe. However, in other countries, they are permitted, for example, in the US. Sodium sorbate (previously had the E number E201) is not an approved food additive in the EU for its genotoxicity.
Calcium sorbate (previously had the E number E203) was no longer allowed to be used in the European Union since Jan, 2018 as the EFSA was not able to evaluate its safety due to the lack of data, such as genotoxicity data, also, it was unable to set an ADI. Therefore this ingredient was deleted in the list of food additives.
FOOD
Sorbic acid can prevent the spoilage of yeast, mold, and some bacteria in food and therefore prolong food shelf life. It can be used to preserve foods with low water content and the following food may contain it:
• cheese
• dried fruit
• yogurt
• pet foods
• dried meats
• baked goods.
While in liquid form/aqueous systems for preservation, potassium sorbate is preferred.
How to use it?
Sorbic acid can be added in food with several methods:
• directly used
• dusted in powder form
• sprayed onto the food surface
• dipped into sorbate solutions to prepare a certain concentrations
• packaging materials
COSMETICS
Sorbic acid can also be used as a preservative in cosmetics and personal care products to inhibit the growth of yeast and mold.
Is Sorbic Acid Safe to Eat?
Yes, it has been approved as a safe ingredient by the U.S. Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA), as well as Joint FAO/WHO Expert Committee on Food Additives (JECFA).
FDA
It is generally recognized as safe (GRAS) that can be used as a chemical preservative in accordance with good manufacturing practice for human consumption.
Uses limit
It is authorized in the following food:
Cheeses and cheese related products < 0.2%
cheeses and cheese related products, used alone or combined with potassium or sodium sorbate < 0.3%
Art sw fruit jellies, pres, and jams < 0.1%
Concentrated orange juice < 0.2%
Margarine <0.1% alone or <0.2% in combination with other preservatives
EFSA
Sorbic acid (E200) is listed in Commission Regulation (EU) No 231/2012 as an authorised food additive and categorized in “Additives other than colours and sweeteners” (7).
Approved uses :
The same with that of potassium sorbate, at the maximum dosage from 20 to 6,000 mg/kg
SAFETY
The LD50 value of sorbic acid is estimated to be between 7.4 and 10 g/kg. Sorbic acid and sorbates therefore have a very low mammalian toxicity – hence their extensive use in food and beverage preservation. Sorbic acid occurs naturally in wild berries, is relatively unstable and rapidly degraded in soil, hence it is considered environmentally friendly. In the body it is generally metabolized by the same oxidation pathway as the 5-carbon saturated fatty acid caproic acid. There is a general consensus that sorbic acid and sorbates are intrinsically devoid of carcinogenic activity. However they have been shown to have the potential to undergo conversion to potential mutagens either through oxidation, or through a chemical reaction with nitrites at pH of 2-4.2 – the latter conditions being ones that mimic the gastric environment. In living yeast cells sorbic acid enhances oxygen free radical formation by the mitochondrial electron transport chain, leading to damage to the mitochondrial DNA.
The U.S. Food and Drug Administration considers sorbic acid to be safe for regular use, as it’s not linked to cancer or other major health problems. Some people can be allergic to sorbic acid, but reactions are typically mild and consist of light skin itching.
While rare, allergic contact dermatitis may occur, but, ironically, over-the-counter corticosteroid creams that contain sorbic acid are often the culprit. People with eczema should avoid sorbic acid in cosmetics because of possible irritation, but avoiding it in foods is unnecessary.
If your skin reacts badly to sorbic acid, you can treat it by rinsing the affected area with water, and applying anti-itch cream. If it’s causing you problems internally, drinking eight ounces of water typically reduces symptoms.
While extremely rare, toxic reactions to sorbic acid can occur when handling it in its pure, undiluted form. In these cases, the National Library of Medicine’s Toxicology Data Network recommends washing your skin and clothes. If inhaled, moving the person to fresh air is recommended. While extremely rare, you may require hospitalization if you experience anaphylaxis. This is a severe allergic reaction that can cause you to go into shock, go pale, get a rash, and experience nausea and vomiting.
EXPOSURE
Workers that use sorbic acid may breathe in vapors or have direct skin contact. The general population may be exposed by consumption of foods and dermal contact with consumer products containing sorbic acid. If sorbic acid is released to the environment, it will be broken down in air. It is expected to be broken down by sunlight. It will not move into air from moist soil and water surfaces. It is expected to move quickly through soil. It will be broken down by microorganisms, and is not expected to build up in fish.
RISK
Use of sorbic acid as a food additive is generally recognized as safe by the U.S. Food and Drug Administration. Skin and eye irritations and allergic reactions have been reported in some people using personal care products containing sorbic acid. No data on additional toxic effects of sorbic acid in humans were available. No toxic effects were observed in laboratory animals fed diets containing moderate-to-high levels of sorbic acid. Tumors were not induced in laboratory animals fed diets containing sorbic acid over their lifetime. Severe stomach irritation, decreased food consumption and body weight, increased abortion, and death were observed in laboratory rabbits given very large oral doses of sorbic acid during pregnancy. Study authors suggest that these effects were due to the antimicrobial effects of sorbic acid in the intestines (killing of natural flora), which led to malnutrition. No evidence for increased abortion or birth defects were observed in laboratory rats given very large oral doses of sorbic acid during pregnancy; however, decreases in maternal body weight and impaired growth and development in offspring were observed. As in the rabbit study, study authors attributed these findings to malnutrition rather than direct toxic effects of sorbic acid. The potential for sorbic acid to cause cancer in humans has not been assessed by the U.S. EPA IRIS program, the International Agency for Research on Cancer, or the U.S. National Toxicology Program 13th Report on Carcinogens. (SRC)
Sorbic acid has proven vital to our ability to store food and transport it across long distances. Allergies are rare and usually very mild, but exposure to undiluted sorbic acid might carry some risks.
Frequently Asked Questions
Is it Natural or Synthetic?
It is natural if it comes from the fruits, however, mostly sorbic acid in the market is synthetic as made from chemical production.
Is it Vegan?
Yes, it is vegan and manufactured without the use of animal matter or products derived from animal origin. So it can be used in the food for vegetarians.
Sorbic acid vs Ascorbic acid?
Some people may be mistaken these two different categories of food additives, sorbic acid is a preservative while ascorbic acid (vitamin c) is an antioxidant and also a vitamin c supplement.
