E1520 - Propylene Glycol
What it is and how it is used
Propane-1,2-diol — propylene glycol — is a clear, slightly sweet, syrupy liquid made from propylene oxide. It should not be confused with ethylene glycol, the toxic antifreeze it is sometimes carelessly likened to; the two are different substances with very different toxicology, and propylene glycol is the one used deliberately in food, medicines and cosmetics.
In food its role is as a carrier solvent and humectant. It dissolves flavourings, colours and extracts that will not dissolve in water or in oil alone — which is why almost every bottle of food colouring and many natural flavour extracts are propylene glycol solutions — and it holds moisture in soft baked goods and icings so they stay soft rather than drying to a crust.
Foods commonly containing it
Food colourings and flavour extracts (as the solvent), icings and frostings, soft baked goods, some ice creams and cake mixes, and as a carrier in food supplements.
Safety summary
Propane-1,2-diol is authorised in Great Britain as E 1520.
The Scientific Committee on Food established an acceptable daily intake of 25 mg per kg of body weight per day in 1996. EFSA completed a re-evaluation in 2018 and concluded there was no reason to revise it. The Panel also found that mean and high-percentile exposures in the brand-loyal refined scenario did not exceed the ADI in any population group at reported use levels.
Known concerns
It is frequently confused with ethylene glycol (antifreeze). They are different compounds: ethylene glycol is metabolised to oxalic acid and is acutely toxic; propylene glycol is metabolised to lactic acid and is not. The confusion is worth naming because it circulates widely.