Potassium Benzoate

About This Product

Potassium benzoate is the potassium salt of benzoic acid, listed as food additive E212 in the EU and UK. Its CAS number is 582-25-2, its formula C7H5KO2 and its molar mass 160.21 g/mol for the anhydrous salt. Food grades are white, practically odourless granules or powder that dissolve very readily in water. It exists to do exactly what sodium benzoate does, preserving acidic foods and drinks against yeasts and moulds, without adding sodium.

That makes it the preservative of choice in reduced-sodium and no-added-sodium soft drinks, sugar-free and diet drinks, juice drinks, squashes, syrups, sauces, dressings and acidic fruit preparations, particularly where a nutrition claim or a sodium reformulation target applies. Antimicrobial activity comes from undissociated benzoic acid, so the working range is the same as for sodium benzoate: most effective at pH 4.5 or below and ideally at pH 4.0 or lower. Typical use levels are in the region of 0.02 % to 0.1 % of the finished product, lower in drinks, and always within the category maximum.

Because potassium is heavier than sodium, the conversion matters. 1 kg of anhydrous potassium benzoate provides about 0.762 kg of benzoic acid, compared with about 0.847 kg from sodium benzoate, so about 1.11 kg of potassium benzoate replaces 1 kg of sodium benzoate at equal preservative strength. Commercial material is normally the anhydrous salt, but hydrated forms exist, so confirm the form and use the assay on the certificate of analysis for exact dosing. At normal preservative levels the potassium contribution rarely affects taste, although the benzoate itself can add sharpness at the top of the range.

The same formulation cautions apply as for other benzoates. With ascorbic acid, heat, light and metal ions, trace benzene can form in drinks, so recipe, packaging and storage need to be managed and tested. Potassium benzoate inhibits baker's yeast, so it has no place in yeast-raised dough. It is often blended with potassium sorbate, keeping the whole preservative system sodium-free while covering a wider pH range.

Key specification parameters are the assay on the dried basis, loss on drying for the form supplied, acidity or alkalinity, chlorinated organic compounds, and lead and other heavy metals. The grade should meet the E212 purity criteria in Regulation (EU) No 231/2012 or its GB equivalent, or the FCC or JECFA specification where required. Permitted food categories and maximum levels are set in Annex II of Regulation (EC) No 1333/2008 and the UK retained equivalent, expressed as benzoic acid and often as a combined limit with sorbates; check the current annex for your category.

Store sealed bags in a cool, dry area away from acids and oxidising agents, and control dust when tipping. When you enquire, tell us the application and its pH, whether you are replacing sodium benzoate and at what dose, the physical form and standard required, the pack size, annual volume and destination, and the documents you need, such as the specification, safety data sheet and a batch certificate of analysis.