Propyl gallate

• BPPropyl Gallate
• Ph. Eur.Propyl Gallate
• USP–NFPropyl Gallate

Gallic acid propyl ester; n-propyl gallate; propylis gallas; propyl 3,4,5-trihydroxybenzoate; Progallin P; Tenox PG; E310

Propyl 3,4,5-trihydroxybenzoate · [121-79-9]

UNII 8D4SNN7V92 · PubChem CID 4947

C10H12O5 · 212.20

Antioxidant, chelating agent

Typical concentrations: up to 0.1% · Dosage forms: Semi-solid

An antioxidant used to prevent the rancidity of fats and oils and the oxidation of oxygen-sensitive drugs and excipients in oral, topical and parenteral preparations, foods and cosmetics. It is used at low concentrations, typically up to about 0.1%, often together with BHA or BHT (for synergy) and a chelating agent such as citric acid. In EU food law, gallates are generally limited to 200 mg/kg of fat, alone or combined with other antioxidants.

A white to creamy-white, crystalline powder, odourless or almost odourless, with a bitter, astringent taste.

Melting point

146–150 °C

Solubility

slightly soluble in water; freely soluble in ethanol and ether; slightly soluble in fixed oils

Function

phenolic free-radical scavenger; synergistic with BHA and BHT

Propyl gallate is light-sensitive and is discoloured by traces of iron and other metals and in alkaline conditions; it is also lost at high temperatures, as in frying. Store in a well-closed, light-resistant container, away from contact with metals, in a cool, dry place.

Forms dark blue-black complexes with iron salts and is incompatible with other metal ions, strong oxidising agents and alkalis. Contact with metal equipment should be avoided.

Prepared by esterification of gallic acid with n-propanol, followed by purification and crystallisation.

At the levels used it is generally regarded as of low toxicity after oral use, being hydrolysed to gallic acid. Contact dermatitis and skin sensitisation have been reported, particularly from cosmetics. EFSA re-evaluated propyl gallate in 2014 and established an ADI.

Observe normal precautions for the quantity handled. Eye protection and gloves are recommended; avoid inhaling the dust.

GRAS listed. Accepted as a food additive in Europe (E310) and evaluated by JECFA. Included in the FDA Inactive Ingredient Database (including oral, topical and injectable preparations) and in non-parenteral medicines licensed in Europe.

Butylated hydroxyanisole; butylated hydroxytoluene; dodecyl gallate (E312); octyl gallate (E311).

Because of its limited oil solubility, propyl gallate is often dissolved first in a small amount of ethanol or propylene glycol before being added to an oil. Combining it with a chelating agent reduces both metal-catalysed oxidation and discolouration.