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Introduction
E479b is a unique and controversial food additive produced by heating soybean oil to high temperatures (typically 180-250°C) in the presence of air, causing thermal oxidation, and then reacting the oxidized oil with mono- and diglycerides. This process creates a complex mixture of oxidized fatty acid oligomers, cross-linked glycerides, and modified mono/diglycerides. The resulting product is highly lipophilic with an HLB value of approximately 1-3. E479b is used almost exclusively as an emulsifier and anti-spattering agent in margarines, frying oils, and industrial cooking fats. It is approved in the EU but has been the subject of safety concerns due to the presence of oxidized compounds. It is not approved in the USA, Japan, Australia, or many other countries. The "b" suffix indicates it is a modified version of E479 (which is no longer used).
CAS Number
Mixture, no specific CAS. Thermally oxidized soybean oil: 68956-68-3 (generic for oxidized vegetable oils).
Synonyms
Thermally oxidized soybean oil interacted with mono- and diglycerides, TOSOM, Oxidized soybean oil emulsifier, E479b, Oxidized fat emulsifier.
Topic Headings
1. Chemical nature and production process (detailed paragraph form)
The production of E479b involves two main steps. First, refined soybean oil is heated to 180-250°C while air (or oxygen) is bubbled through it for 2-8 hours. During this thermal oxidation, several reactions occur: hydroperoxides form from unsaturated fatty acids (linoleic and linolenic acids are most susceptible); these hydroperoxides decompose into aldehydes, ketones, and short-chain fatty acids; and, importantly, polymerization occurs via free radical mechanisms, creating dimers and oligomers of fatty acids (mainly C18 dimers and trimers linked by carbon-carbon, ether, and peroxide bonds). The second step involves reacting this oxidized oil with mono- and diglycerides (typically E471) at 150-200°C for 1-2 hours. The mono/diglycerides esterify with free carboxyl groups on the oxidized fatty acid oligomers, increasing the product's compatibility with fat systems. The final product is a dark amber to brown viscous liquid or soft paste with a characteristic "cooked oil" odor. The degree of oxidation is controlled by measuring peroxide value (PV) and anisidine value (AV); typical specifications require PV <10 meq/kg (after stabilization) and AV <30.
*2. Mechanism of anti-spattering action in margarine (paragraph form)*
When margarine is heated in a frying pan, water droplets (dispersed in the fat phase) turn to steam. If the steam escapes slowly, it causes the fat to "spatter" — small droplets of hot fat are ejected violently from the pan, creating safety hazards and mess. E479b prevents spattering through a unique mechanism. The polar oxidized components in E479b (aldehydes, ketones, carboxylic acids, and oligomers) adsorb strongly at the fat-water interface. During heating, as water turns to steam, these polar molecules form a stable, viscoelastic film around each steam bubble. This film slows the release of steam, allowing it to escape through small pores rather than bursting violently. The result is a quiet, controlled release of steam with minimal fat ejection. At 0.3-0.7% E479b in margarine, spattering is reduced by 80-95% compared to margarine without additive. In frying oils (not emulsions), E479b has a different effect: it reduces the surface tension of the oil, allowing it to spread more evenly on food surfaces and reducing the amount of oil absorbed during frying.
3. Applications and typical usage levels (list form)
• Margarine and low-fat spreads — 0.3-0.7% reduces spattering during frying; improves texture and spreadability at refrigerator temperatures.
• Industrial frying oils (for potato chips, french fries) — 0.1-0.3% reduces oil absorption by 10-15%; gives crispier texture; extends oil life by 20-30%.
• Pan release agents (sprays for baking pans) — 0.5-1.5% improves non-stick properties; allows even coating.
• Shortenings for commercial baking — 0.2-0.5% improves creaming properties in cookie and cake doughs; gives better volume and texture.
• Deep-frying fats for donuts and pastries — 0.2-0.4% reduces fat pickup; improves golden color development.
• Popcorn oils — 0.1-0.2% improves oil adhesion to popcorn kernels; reduces unpopped kernels.
4. Chemical and physical properties (list form)
• Appearance — Dark amber to brown viscous liquid or soft paste.
• Odor — Characteristic cooked oil or slightly rancid odor (not unpleasant at low concentrations).
• Melting range — 20-40°C (soft paste at room temperature; liquid when warm).
• Solubility — Soluble in fats and oils; insoluble in water; slightly soluble in ethanol.
• HLB value — 1-3 (extremely lipophilic).
• Acid value — 5-25 mg KOH/g (higher than most emulsifiers due to oxidized acids).
• Saponification value — 180-250 mg KOH/g (lower than non-oxidized esters due to polymer formation).
• Peroxide value — Typically <10 meq/kg after stabilization with antioxidants.
• Anisidine value — 10-30 (indicates secondary oxidation products; higher in more oxidized batches).
• Viscosity — 500-2000 cP at 40°C (much higher than unoxidized oils).
• Dimer/oligomer content — 15-40% (by gel permeation chromatography).
• Iodine value — 60-100 (reduced from original soybean oil due to oxidation and polymerization).
5. Stability and storage considerations (paragraph form)
E479b is already partially oxidized by design, so it is more stable than unoxidized oils but still requires careful storage. The product should be stored in sealed, light-protected containers (preferably stainless steel or dark glass) under an inert gas blanket (nitrogen) to prevent further oxidation. Storage temperature should be below 25°C; at higher temperatures, residual antioxidants (tocopherols) degrade and oxidation accelerates. Shelf life is typically 6-9 months under optimal conditions (compared to 12-18 months for non-oxidized emulsifiers). Once opened, E479b should be used within 3 months. Do not store in plastic containers that contain metal catalysts (e.g., certain PVC grades). Over time, E479b may develop a stronger rancid odor and darker color; if the peroxide value exceeds 20 meq/kg or the anisidine value exceeds 50, the product should be discarded as it may negatively affect food flavor. For long-term storage (over 3 months), refrigeration (4-8°C) is recommended. Do not freeze — freezing can cause phase separation and texture changes.
6. Safety, toxicity, and regulatory restrictions (detailed paragraph form)
E479b is one of the most controversial food additives due to the presence of thermally oxidized compounds. When soybean oil is heated to high temperatures in air, it forms potentially harmful substances including oxidized triglycerides, cyclic fatty acid monomers, glycidol esters, and 3-monochloropropane-1,2-diol (3-MCPD) esters. Some of these compounds have shown genotoxic and carcinogenic effects in animal studies at high doses. For this reason, E479b is not approved in the USA (FDA does not list it as a direct food additive), Japan, Canada, Australia, New Zealand, or Switzerland. It remains approved in the EU under Regulation (EC) No 1333/2008, but with strict purity criteria: 3-MCPD content must be below 1 mg/kg, glycidol esters below 0.5 mg/kg, and cyclic fatty acid monomers below 15% of total fatty acids. JECFA evaluated E479b in 2007 and established a temporary ADI of 0-3 mg/kg body weight, pending further toxicological data. The European Food Safety Authority (EFSA) re-evaluated E479b in 2013 and concluded that the current ADI (3 mg/kg) is adequate but recommended continued monitoring. Typical intake in European populations is estimated at 0.5-1.5 mg/kg/day. Consumer advocacy groups have called for a ban on E479b, and many European food manufacturers have voluntarily replaced it with alternative anti-spattering agents (lecithin, E471, or silica). Pregnant women and children are advised to limit intake of foods containing E479b when possible. No allergic reactions have been reported specifically to E479b, but individuals with soybean allergies should avoid it because trace soy protein residues may remain (typically <1 ppm).
7. Analytical methods for quality control (list form)
• Peroxide value (PV) — Measures primary oxidation products (hydroperoxides); titrimetric method (iodometric) or spectrophotometric (ferric thiocyanate).
• Anisidine value (AV) — Measures secondary oxidation products (aldehydes); spectrophotometric at 350 nm after reaction with p-anisidine.
• Total oxidation value (TOTOX) — Calculated as 2PV + AV; gives overall oxidation status; typical target <30 for E479b.
• Free fatty acids (acid value) — Titration with KOH; indicates hydrolytic degradation.
• Polymer content — Gel permeation chromatography (GPC) separates monomers, dimers, trimers, and higher oligomers.
• 3-MCPD and glycidol esters — GC-MS after derivatization with phenylboronic acid; critical for regulatory compliance in EU.
• Cyclic fatty acid monomers — GC after hydrogenation and methylation; quantifies potentially toxic cyclized products.
• Fatty acid profile — GC after methylation; compares to unoxidized soybean oil to assess changes.
• Color measurement — Lovibond or spectrophotometric at 420-450 nm; darker color indicates higher oxidation.
• Viscosity measurement — Rotational viscometer at 40°C; higher viscosity indicates more polymerization.
