Maillard reaction

Maillard browning is crust color and roast aroma from proteins plus sugars under heat, once the surface is dry enough to brown rather than steam. It is not Caramelization, which is sugar cooking on its own. The onset depends on the ingredients, surface moisture, and heat transfer.

What the baker actually controls #

King Arthur’s steam guide: fill the chamber early so the crust stays moist and extensible; then vent — about twenty minutes into a typical home hearth bake, in their account — so the crust can brown and firm in a dry oven ¹. The first half is oven spring and surface Gelatinization. The second half is when browning has a chance. Calvel treats the oven as the last of several linked operations, not a color commandment ².

A pale loaf can be underbaked, steamed too long, or mixed so hard that flour pigments were already bleached. King Arthur, following Calvel, notes that intensive mixing can over-oxidize carotenoid pigments and leave bread paler, with less aroma ³. That is mixing damage, not a missing Maillard switch.

What to observe #

Look. Color should move through straw to deep brown, not to black. Black is burning.

Smell. Baked crust smells toasted and wheaty. Burnt smells like carbon. Caramel smells like cooked sugar; if you only cooked sugar, you are on the Caramelization page.

Feel. A browned crust that is still leathery needed more dry time after steam, not a hotter slogan.

Failure modes #

• Pale, thick crust. Steam never left, or the oven never dried. Quality.
• Dark before the crumb is set. Heat too fierce on the surface; the inside is a Heat transfer problem.
• Calling every brown food Maillard. Jam that darkens from a long boil is concentrated fruit and sugar; bread crust is a different conversation. See Sugar and Jam.

Action: bake with steam, then dry heat. Judge doneness by crumb set and crust color together. Baking the loaf is the craft sequence.