Short answer
Caramelisation is sugar breaking down under heat on its own, without the amino groups the Maillard reaction needs. Sugars lose water, fragment and recombine into brown polymers and flavour compounds, going from pale gold to deep brown and then bitter black. Industrial caramel colour, the most widely used food colour by volume, is made by the same controlled heating of carbohydrates, sometimes with acids, alkalis, sulfites or ammonium compounds, which define its four classes.
Heat sucrose dry or in a little water and nothing visible happens until the water has gone and the syrup climbs well above boiling. Then the sugar splits into glucose and fructose, which lose water and break into smaller fragments; those fragments recombine into larger coloured molecules. The colour deepens steadily and the flavour moves from sweet through buttery and nutty to bitter as the balance of products shifts. Different sugars break down at different rates, and fructose-rich syrups such as honey tend to darken sooner than plain sucrose syrup, though published onset temperatures vary so much with moisture and heating rate that no single figure is worth quoting.
Cooks judge caramel by colour because it tracks the chemistry closely: a pale straw syrup is still mostly sugar, a mid-amber caramel has the balance of sweetness and roasted notes most recipes want, and a mahogany caramel is bitter and seconds away from burning. Judging it well needs good light. Under warm household lighting a caramel looks deeper than it is, and a dark pan hides colour; a white saucer and a drop of caramel, viewed in daylight or a neutral lamp, gives a truer reading.
A caramel keeps cooking from the pan's stored heat after it leaves the hob; take it off a shade lighter than you want.
Caramel colour for colas, dark beers, sauces, gravies and baked goods is made commercially by heating carbohydrates under controlled conditions. International specifications divide it by what else is present during heating: Class I plain caramel uses no ammonium or sulfite compounds; Class II uses sulfite compounds; Class III uses ammonium compounds; Class IV uses both. The classes differ in charge, stability in acid and alcohol and in the foods they suit — a cola needs a colour that stays dissolved in an acidic drink, while a beer needs one that tolerates alcohol and proteins. In the EU they are E 150a to E 150d.
In real food the two reactions run together whenever sugar and protein are both present and the temperature is high. A pure sugar syrup can only caramelise; a milk caramel or dulce de leche browns mainly through Maillard chemistry at much lower temperatures, because the milk proteins supply amino groups. That is why dulce de leche can darken gently for hours in a water bath while a sugar caramel needs a very hot pan. The colour can look alike; the flavour and the conditions are different.
| Class | Name | Made with | INS / EU number |
|---|---|---|---|
| I | Plain caramel | Carbohydrate heated with or without acid or alkali; no ammonium or sulfite compounds | 150a / E 150a |
| II | Sulfite caramel | As Class I, in the presence of sulfite compounds | 150b / E 150b |
| III | Ammonia caramel | As Class I, in the presence of ammonium compounds | 150c / E 150c |
| IV | Sulfite ammonia caramel | As Class I, with both sulfite and ammonium compounds | 150d / E 150d |
Why: Residual heat in the pan keeps the reaction going.
Fix: Stop a shade early and cool the base of the pan in water.
Why: Warm, dim lighting and a dark pan make amber read as brown.
Fix: Test a drop on a white saucer under neutral light.
Each statement is labelled by kind — established fact, a standard’s requirement, observed market data, a convention, or Colourwise’s own interpretation or analysis — with the strength of the evidence behind it.
StandardStrong evidence
Caramel colours are divided into four classes by the reactants used during heating of carbohydrates: Class I plain caramel (no ammonium or sulfite compounds), Class II sulfite caramel, Class III ammonia caramel and Class IV sulfite ammonia caramel, numbered INS 150a to 150d.
Source: Caramel Colours — specifications (FAO JECFA Monographs 11)
FactStrong evidence
In the EU, plain caramel, caustic sulphite caramel, ammonia caramel and sulphite ammonia caramel are listed as food colours E 150a, E 150b, E 150c and E 150d.
Source: Food colours (topic page)
FactStrong evidence
The Maillard reaction requires amino compounds and is classed with caramelisation as non-enzymatic browning, whereas enzymatic browning is an oxidation of phenolic compounds.
Reviewed 29 September 2026. Colourwise summarises its sources in its own words and does not reproduce standards text or proprietary colour data. Spotted an error? Tell us.