Sodium Benzoate

About This Product

Sodium benzoate is the sodium salt of benzoic acid and is listed as food additive E211 in the EU and UK. It has the CAS number 532-32-1, the formula C7H5NaO2 and a molar mass of 144.10 g/mol. Food grades are white, practically odourless powder, granules or extruded pellets; the choice between them is about dust, flow and dissolving speed. Sodium benzoate is freely soluble in water, far more so than benzoic acid itself, which is why the salt is the normal choice for liquid products.

In an acidic product the salt releases benzoic acid, and it is the undissociated acid that inhibits yeasts and moulds, with weaker activity against bacteria. Benzoic acid has a pKa of about 4.2, so sodium benzoate performs best at pH 4.5 or below and ideally at pH 4.0 or lower. Above about pH 5 most of the acid is dissociated and the preservative contributes little. Typical applications are carbonated and still soft drinks, squashes and cordials, fruit juice drinks, syrups, ketchups, sauces and dressings, pickles and fruit preparations. Typical use levels fall between about 0.02 % and 0.1 % of the finished product, with drinks at the lower end, and always within the maximum for the food category. For dose calculations, 1 kg of sodium benzoate provides about 0.847 kg of benzoic acid.

Sodium benzoate can leave a sharp or slightly burning aftertaste at higher levels, so many soft drinks pair a lower benzoate dose with potassium sorbate, which also extends protection towards pH 6. In drinks that contain ascorbic acid, trace benzene can form, and heat, light and copper or iron ions speed the reaction up; formulators control this through recipe design, chelating agents, packaging, storage conditions and finished-product testing. Where sodium reduction matters, potassium benzoate (E212) delivers the same benzoic acid at a slightly higher addition rate. Benzoates also inhibit baker's yeast, so they are not used in yeast-raised dough.

Buyers normally agree the assay on the dried basis, loss on drying, acidity or alkalinity, lead and other heavy metals, chlorinated organic compounds and readily oxidisable substances. Physical form and particle size or bulk density should be stated wherever dosing equipment or dissolving time matters. The grade should conform to the E211 purity criteria in Regulation (EU) No 231/2012 and its GB equivalent, and to the Food Chemicals Codex or JECFA monograph where an export market asks for it.

Sodium benzoate may be used only in the food categories, and up to the maximum levels, set in Annex II of Regulation (EC) No 1333/2008 and the UK retained equivalent. Maximum levels are expressed as benzoic acid, and many categories set a combined limit for benzoates and sorbates, so convert the salt dose and add both contributions before comparing with the annex. Check the current consolidated annex for your exact category. On the label, declare it by class and name or number, for example preservative: sodium benzoate, or preservative: E211.

Keep bags sealed in a cool, dry store away from strong acids and oxidising agents. The powder takes up moisture and can cake, and fine grades raise dust, so use local extraction and eye protection when tipping. Make up stock solutions fresh in stainless steel or plastic vessels. When you enquire, give the application and finished-product pH, the physical form you prefer, the specification standard you work to (E211, FCC or JECFA), the pack size, annual volume and destination market, and list the documents your approval process needs, such as the specification, safety data sheet and a batch certificate of analysis.