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Introduction
E472c, also called CITREM (citric acid esters of mono- and diglycerides), is an anionic emulsifier produced by esterifying mono- and diglycerides with citric acid. The citric acid molecule has three carboxyl groups and one hydroxyl group, allowing it to form both ester and hydrogen bonds. This gives E472c a unique ability to chelate metal ions (especially calcium and iron) in addition to its emulsifying properties.
The primary applications of E472c are in fat-based systems where oxidative stability is critical. It is widely used in frying oils, margarine, and spray-dried powders. Unlike most other emulsifiers, E472c has a very low HLB value (approximately 1-3), making it highly lipophilic. It functions as both an emulsion stabilizer and an antioxidant synergist by sequestering pro-oxidative metal ions. E472c is approved in EU, USA (as citric acid esters of mono- and diglycerides, 21 CFR 172.832), and Codex.
CAS Number
Mixture: 91052-83-2. Partial esters: 101476-74-4 (stearic acid type).
Synonyms
CITREM, Citric acid esters of monoglycerides, Citroglycerides, Citrated mono- and diglycerides, E472c.
Topic Headings
1. Antioxidant mechanism via metal chelation (detailed paragraph form)
Lipid oxidation is initiated by free radicals generated from the decomposition of hydroperoxides. Transition metals like iron and copper catalyze this decomposition through Fenton-type reactions. E472c inhibits this process through two complementary mechanisms. First, the citric acid portion has three adjacent carboxyl groups that form stable five-membered chelate rings with metal ions. The formation constant (log K) for Fe²⁺-citrate complex is approximately 10.5, meaning that most free iron ions are sequestered. Second, when E472c is positioned at the oil-water interface (as it naturally partitions due to its low HLB), the citrate group extends into the aqueous phase where most metal contaminants reside. This creates a "metal trap" directly at the location where oxidation begins. In frying oils containing 0.05-0.10% E472c, the formation of polar compounds (used to measure oil degradation) is reduced by 40-60% over 8 hours of continuous heating at 180°C. This extends frying oil life by 30-50% compared to untreated oil.
2. Comparative effectiveness of different metal chelators in frying oils (tabular form)
|
Chelator/emulsifier |
Metal binding strength (log K for Fe²⁺) |
Thermal stability at 180°C |
Oil life extension |
HLB |
|---|---|---|---|---|
|
E472c (CITREM) |
10.5 |
High (citrate survives) |
40-60% |
1-3 |
|
EDTA (E385) |
14.3 (stronger) |
Low (decomposes by 150°C) |
<10% |
Not applicable |
|
Citric acid (E330) |
10.5 |
Medium (sublimes partially) |
20-30% |
N/A (water-soluble) |
|
E472a (ACETEM) |
None |
N/A |
0-5% |
2-4 |
|
TBHQ (synthetic antioxidant) |
None |
High |
50-70% |
N/A |
*3. Applications in spray-dried powders and infant formula (paragraph with embedded list)*
Spray-dried powders like coffee creamers, infant formulas, and sports drink mixes require emulsifiers that remain functional after hot-air drying. E472c is particularly valued in infant formulas for three reasons:
In coffee creamer powders, E472c at 0.5-1.0% of total fat prevents oil separation during storage and reduces "oiling off" on the coffee surface after reconstitution. The citrate group also buffers against the acidity of coffee, similar to E472b's mechanism but with less effect on foam.
4. Regulatory status and ADI information (list form)
