Potassium benzoate, the potassium salt of benzoic acid, is used as a preservative to prevent food spoilage by inhibiting the growth of mold, yeast and some bacteria. But this ingredient is used less than the common benzoate preservative – sodium benzoate. The European food additive number for it is E212. Generally, it is safe, synthetic, vegan, halal, kosher and gluten-free.
Potassium benzoate can be chemically synthesized by the reaction of benzoic acid (produced from the oxidation of toluene) with potassium bicarbonate, or potassium carbonate, or potassium hydroxide. Dow Chemical Company came up with a method of obtaining high yield and pure potassium benzoate by reacting benzoic acid with potassium hydroxide. (1)
A white or colorless crystalline powder or granular.
- Potassium salt of benzenecarboxylic acid
- Potassium salt of phenylcarboxylic acid
>300 °C (572 °F; 573 K)
Ester group and aromatic benzene ring. The ester group is easy to react with other groups.
In water: 73.83 g/100 mL (25 °C) in water, approximately 21 times that of benzoic acid, 3.44 g/L (25 °C). It dissociates into two distinct parts in water, the benzoate anion and potassium cation. The benzoate anion is the conjugate base of the benzoic acid.
In organic solvents: soluble in ethanol, slightly soluble in methanol, insoluble in ether.
The pKa of benzoic acid is 4.2. The preservation function is better in low-pH products, below 4.5 or below its pKa.
The mechanism of action is the same with that of sodium benzoate, and also similar to sorbates, but different with the bio preservative – natamycin. Benzoic acid forms when potassium benzoate dissociates in water and combines with proton. The undissociated benzoic acid enters the microbial cell and inhibits cell growth. This is how it works and plays a role in food preservation.
It is used less than sodium benzoate in past years, but now it seems the market demand is increasing. Potassium benzoate is used as a substitute preservative for sodium benzoate primarily in acidic foods where the sodium content needed to be lower. The following food may contain with it:
And let’s have a closer look at what soda manufacturers say about it.
- Coca Cola: used as a preservative and to protect taste. (2)
- Pepsico: in the carbonated soft drinks, such as in Diet Pepsi and Sierra Mist to preserve freshness. (3)
Yes, it has been approved as a safe preservative by European Food Safety Authority (EFSA), as well as Joint FAO/WHO Expert Committee on Food Additives (JECFA), and can be used in wide products such as fruit juice and soft drinks.
Potassium benzoate and sodium benzoate are two salts of benzoic acid, but different with sodium benzoate used as a direct preservative, potassium benzoate is not listed in the Food Additives List for food & beverage (4) and is categorized as an indirect food additive to use in polymers for food contact surfaces. (5)
However, the FDA mentioned potassium benzoate has the same function as sodium benzoate, which may be used to inhibit the growth of bacteria, yeasts, and molds in beverages. There is a potential risk that the heat and light exposure will stimulate the formation of benzene (a known carcinogen) by the reaction of vitamin c (naturally or added) and potassium benzoate in drink. (6)
From the above information from end-users, I think potassium benzoate can be used as a food preservative like sodium benzoate in the USA as Coca Cola and Pepsi also sell its products in the USA, like Diet Pepsi. However, I cannot find solid proof from the FDA official website for its use as a direct food preservative. Please let me know if you have found such information.
Potassium benzoate (E212) is listed in Commission Regulation (EU) No 231/2012 as an authorised food additive and categorized in “Additives other than colours and sweeteners” (7).
Its food application is listed together with benzoic acid, sodium and calcium benzoate (E210-E213), and the maximum used levels range from 150 to 6,000 mg/kg. It can be used with sorbic acid-sorbates (E 200–202) and p-hydroxybenzoates (E 214–219).
Safety Re-evaluation in 2016
After the studies of no genotoxicity, no reproductive toxicity, no carcinogenic potential and other researches, EFSA derived a group ADI of 5 mg/kg bw per day, expressed as benzoic acid. Scientific (8)
UK Food Standards Agency
Categorized in “Preservatives” (9)
Food Standards Australia New Zealand
It is an approved ingredient in Australia and New Zealand with the code number 212. (10)
Function Class: food additives, preservative. (11)
Acceptable daily intake: ADI “5 mg/kg bw” expressed as benzoic acid, set in 1996. (12)
Some people may be afraid the safety of potassium benzoate when watching the house of evil owner said the toppings was bad as it contains potassium benzoate in Simpsons episode (Season 4 – Cursed Frogurt) (13). Is it really bad for you?
Synthesized preservatives are the most controversial food additives although they have been approved safe. That’s why potassium benzoate is generally considered safe but consumers always have health concerns whether it is bad for their health and what are the possible side effects. The following are the most discussed potential adverse effects and the facts:
- Cancer: due to vitamin c turns it to benzene (a known carcinogen) in the beverage. However, the FDA said the levels of benzene (none or below 5ppm)will not pose a safety concern for consumers.
- Allergy: there were allergies to sodium benzoate reported in the EFSA’s 2016 re-evaluation, but without mentioned people allergic to potassium benzoate.
Potassium Benzoate vs Sodium Benzoate?
The purpose of potassium benzoate is used as a low sodium preservative alternative for sodium benzoate in some food.
Does Potassium Benzoate Raise Potassium Level?
Of course, it will increase the potassium level in our body, but very little.
Is Potassium Benzoate Natural?
It is not natural. Potassium benzoate is the salt of benzoic acid. The salt is not found to occur naturally and the manufacturing process through chemical synthesis, so it is not natural.
Now I think you may have a good knowledge of the preservative – potassium benzoate (E212), from the production process, uses, approved safety and possible side effects. Also you may be clear with some common FAQs such as the comparison with sodium benzoate.
What kinds of food labels have you found this ingredient in? Let me know in the comments.