Browning: Maillard, caramelisation and char

Short answer

Most of the colour and toasty flavour on a pizza crust comes from the Maillard reaction between amino acids and reducing sugars, which speeds up markedly once the surface has dried and climbs above roughly 140 °C. Caramelisation of sugars alone needs higher temperatures, and beyond that browning continues into char — carbonised material that is genuinely bitter, pleasant as accents but not as a whole surface.

The Maillard reaction

The Maillard reaction is a cascade of reactions between amino acids (from proteins) and reducing sugars such as glucose and maltose. It produces brown pigments and hundreds of aroma compounds — the toasted, bready, savoury notes of a good crust. It happens slowly at lower temperatures but becomes fast enough to matter in a bake once the surface is somewhere above roughly 140 °C.

The crucial condition is dryness. While a surface is wet, evaporating water holds it near 100 °C and the reaction barely moves. Browning therefore only really starts once the outer layer has dried, which is why a crust that stays damp — from a cool oven, a wet topping load or steam trapped beneath — stays pale.

Caramelisation and the browning-to-char continuum

Caramelisation is sugar breaking down on its own, without protein. It generally needs higher temperatures than the Maillard reaction — often quoted as around 160 °C or above for sucrose, lower for some other sugars — and in pizza it plays a smaller role, most visible where sugar, honey or caramelised toppings are exposed.

Push either process further and the compounds formed start to break down into carbonised material. That is char: black, dry and bitter. On a fast-baked pizza, char is often confined to the thinnest, most exposed points of the rim (leopard spotting), and many people enjoy it as contrast. When it spreads across most of a surface — or across the base — it reads as burnt. There is no single temperature at which browning becomes burning; it depends on how hot, how long and how thin the area is. The sensory guide on char covers the flavour side.

Sugar, malt and milk

Because Maillard browning needs reducing sugars, the sugar available at the surface affects colour. A long ferment can supply sugars through flour enzymes but can also use them up. Doughs designed for lower-temperature domestic and deck ovens, such as many New York-style formulas, often add a little sugar, malt or oil partly so that they brown within a longer bake at lower heat. Diastatic malt adds enzymes that release more sugar from starch; milk or milk powder adds lactose and protein, both of which encourage browning.

At very high temperatures the same additions can make a crust burn before the bake is done, which is one reason Neapolitan-style doughs for very hot ovens typically contain no added sugar.

Why pale crusts happen

A pale crust usually traces back to one of three things: not enough heat at the surface (oven or baking surface not fully preheated, or too low a setting), too much moisture keeping the surface near 100 °C, or too little available sugar (an overfermented dough, or a low-temperature bake with no added sugar). A base that is pale while the top is brown is usually a conduction problem — the surface under it was not hot enough or does not transfer heat fast enough.

Common misconceptions

“Browning on bread and pizza is caramelisation.”

Most crust browning is the Maillard reaction, which involves proteins as well as sugars. Caramelisation contributes, especially with added sugar, but is not the main source.

“Darker is always more flavourful.”

Flavour builds with browning up to a point, then turns bitter as material carbonises. Small charred spots can add contrast; widespread char mostly adds bitterness.

“Adding sugar is the fix for every pale crust.”

Sugar helps in lower-temperature bakes, but if the oven or surface is too cool or the crust too wet, sugar alone will not brown it, and in very hot ovens it can cause burning.

What this page cannot tell you

Temperatures for the Maillard reaction and caramelisation are approximate and depend on moisture, acidity and which sugars are present; published figures vary. This page does not address the health questions around high-temperature browning, and PizzaHQ has not measured browning in any dough.

Related

Evidence

• A review of Maillard reaction in food and implications to kinetic modelling — Trends in Food Science & Technology (Elsevier), vol. 11, nos. 9–10, pp. 364–373
• Browning development in bakery products – A review — Journal of Food Engineering (Elsevier), vol. 99, no. 3, pp. 239–249
• On Food and Cooking: The Science and Lore of the Kitchen (revised edition) — Scribner
• How to make pizza crust crispy (and why yours isn't browning) — King Arthur Baking Company
• Pizza Crust Lacks Browning? Causes & Fixes — PizzaBlab