E479b - Thermally oxidised soya bean oil interacted with mono- and diglycerides of fatty acids
What it is and how it is used
The full name is a description of the process. Soya bean oil is heated in air until it partly oxidises and polymerises, then reacted with mono- and diglycerides of fatty acids. Trade and regulatory texts abbreviate the result to TOSOM.
It has one job, and it is a narrow industrial one: it stops frying oil foaming and breaking down in continuous commercial fryers. Oil in a deep-fat fryer degrades as it is used, and a small amount of TOSOM extends the usable life of a batch and keeps the surface stable. It is not an ingredient of a recipe so much as a treatment applied to the oil the food is cooked in.
Foods commonly containing it
Frying oils and fats used in commercial and industrial deep-frying. It is not typically added to a finished retail food, though residues may carry through on fried products.
Safety summary
TOSOM is authorised in Great Britain as E 479b.
The historic acceptable daily intakes are 25 mg/kg bw/day from the Scientific Committee for Food and 30 mg/kg bw/day from JECFA. EFSA re-evaluated the additive in 2018 and reached a more cautious position: the Panel found the available toxicological data insufficient to support the current ADI, specifically noting the absence of absorption and metabolism data and the lack of developmental toxicity studies. It identified a no-observed-adverse-effect level of 5,400 mg/kg bw/day — the highest dose tested — in a chronic rat study, and found no adverse effects in a limited subchronic study in pigs.
In plain terms: nothing harmful has been demonstrated, but EFSA judged the dataset too thin to confirm the existing safety margin. That is a data gap rather than a finding of harm, and it is the honest summary of where this additive stands.
Known concerns
EFSA's 2018 conclusion that the dataset does not support the current ADI is itself the standing concern. It is soya-derived; UK allergen labelling rules require soya to be declared where it is present as an allergen.