E-numbers / Thickeners & emulsifiers / E479b
also: TOSOM · oxidised soya bean oil with mono- and diglycerides
An emulsifier made from heat-treated soya oil, used almost exclusively in industrial frying fats to stop them separating.
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EFSA's 2018 re-evaluation found no genotoxicity data and no developmental or reproductive toxicity studies exist for this substance, leaving key toxicological gaps unresolved.
UK supermarket foods that declare E479b: 3 of the 43,325 we checked (under 0.1%)
Counted by its code or its name in the ingredient list.
Counted by NutraSafe from UK supermarket ingredient lists, September 2026. How we counted
Why it’s worth knowing. EFSA's 2018 re-evaluation found no genotoxicity data and no developmental or reproductive toxicity studies exist for this substance, leaving key toxicological gaps unresolved.
E479b is produced by thermally oxidising soya bean oil at high temperature, then reacting the oxidised oil with mono- and diglycerides of fatty acids to form a complex mixture of oxidised and esterified lipid compounds. The abbreviation TOSOM (thermally oxidised soya bean oil interacted with mono- and diglycerides of fatty acids) is sometimes used in technical literature.
It acts as an emulsifier, reducing surface tension between fat and water and stabilising high-fat emulsions. In frying-fat applications it helps maintain a stable liquid emulsion at high temperatures, preventing the fat and any water-based components from separating during cooking.
Used almost exclusively in fat emulsions for frying purposes, such as industrial frying shortenings and liquid frying fats used in commercial food production. Consumer products are rarely labelled with it directly; where present it appears on the ingredients list as 'emulsifier (E479b)' or 'emulsifier (thermally oxidised soya bean oil interacted with mono- and diglycerides of fatty acids)'.
When EFSA's Panel on Food Additives and Flavourings re-evaluated E479b in 2018, it identified three significant data absences: no absorption, distribution, metabolism or excretion (ADME) data; no genotoxicity studies of any kind; and no adequate developmental or reproductive toxicity studies. These gaps mean the existing ADI cannot be fully supported by the current evidence base, even though the margin between estimated consumer exposure and the doses used in animal studies is large.
No genotoxicity data were available for E479b; the Panel was therefore unable to assess whether the substance or its degradation products carry a genotoxic hazard.
No developmental or reproductive toxicity studies with adequate reporting were available, leaving the safety of E479b during pregnancy and foetal development uncharacterised.
The Panel concluded the toxicological data available were insufficient to support the previously established ADI of 25mg/kg body weight per day set by the Scientific Committee on Food.
The primary long-term study used to assess E479b was a 2.5-year rat chronic and carcinogenicity study. No adverse effects were observed up to the highest dose tested (5,400mg/kg body weight per day in males), and EFSA calculated that estimated maximum human exposure at the 95th percentile for toddlers reaches roughly 10mg/kg body weight per day, giving a margin of safety of approximately 540-fold against the animal NOAEL. The limitation is that the NOAEL is also the highest dose tested, so the true no-effect level could be lower.
A 2.5-year rat study found no observed adverse effects at the highest dose tested of 5,400mg/kg body weight per day (males); this dose was used as the NOAEL.
Estimated maximum dietary exposure to E479b reached 10.1mg/kg body weight per day at the 95th percentile for toddlers, yielding a margin of safety of approximately 540 compared to the animal NOAEL.
E479b is derived from soya, which is a declarable allergen under UK food law. The manufacturing process involves high-temperature oxidation and chemical reaction, which may alter or degrade the soya proteins that typically trigger allergic responses. Regulators have not formally exempted E479b from allergen labelling obligations in the way that highly refined oils are sometimes treated, so individuals with soya allergy or intolerance should treat its presence on a label with caution.
Soya is listed as a major allergen requiring declaration under UK food law (assimilated EU Regulation 1169/2011, Annex II). Highly refined soya oil is exempt from allergen labelling, but E479b is a chemically modified derivative rather than a simple refined oil.
People with a soya allergy should note this additive is derived from soya. On the label it appears as 'emulsifier (E479b)'. The allergen status of highly processed soya derivatives is uncertain, so those with a confirmed soya allergy should check with their allergy dietitian before consuming products containing it.
E479b is a narrow-use industrial additive, found in commercial frying fats rather than everyday supermarket products, so most people's exposure is low. The science here is incomplete rather than alarming: a large margin exists between the doses shown to be harmless in long-term animal studies and the estimated human intake, but the absence of genotoxicity and reproductive toxicity studies means regulators could not fully validate the historical ADI when they looked again in 2018. Those gaps have not been filled publicly since. That is an honest statement of the evidence, not a clearance.
No. E479b is permitted in the UK under assimilated EU Regulation 1333/2008, restricted to fat emulsions used specifically for frying purposes at a maximum level of 5,000mg/kg.
EFSA's re-evaluation found that no genotoxicity studies and no developmental or reproductive toxicity studies had ever been conducted on E479b. This meant the panel could not confirm the historical acceptable daily intake was fully supported by evidence, though it also found no evidence of harm in the animal studies that do exist.
E479b is used almost exclusively in industrial frying fats and fat emulsions for frying. It is rarely present in consumer retail products; if it does appear, it will be declared as 'emulsifier (E479b)' in the ingredients list.
Yes. E479b is derived entirely from plant sources: soya bean oil and plant-derived mono- and diglycerides of fatty acids. It contains no animal products.
Last reviewed: 20 June 2026
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