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The Maillard reaction

Also called browning reaction

The reaction between amino acids and reducing sugars that browns food and creates hundreds of new flavour compounds.

140–180 °C (284–356 °F)

What it is

It is not one reaction but a cascade. Amino acids and sugars combine, rearrange and fragment, building colour and aroma molecules that were not in the raw ingredient at all. Roast meat, bread crust, coffee, chocolate, toasted nuts and fried onions all taste of it.

Why it works

It needs a surface above roughly 140 °C, which means a dry surface: while water is boiling off, the surface is pinned near 100 °C and cannot get there. It goes faster in alkaline conditions, which is why a pinch of bicarbonate speeds up onion browning and why pretzels are dipped in lye.

When to use it

Any time you want a cooked ingredient to taste of more than itself.

What goes wrong

Confusing it with caramelisation, which is sugar alone; expecting it in a wet pan; pushing it past brown into black, where the new compounds are bitter rather than savoury.

Meridian cooking encyclopedia — Watchman Productions

More on this shelf

  • Brining and salt What salt does to meat beyond seasoning it.
  • Caramelisation The breakdown of sugar by heat alone into colour, aroma and bitterness.
  • Carryover cooking Food keeps cooking after it leaves the heat, and large pieces keep going a long way.
  • Collagen and gelatin Why tough cuts become tender and rich with long, moist cooking.
  • Fermentation Controlled microbial transformation of food, and the conditions that keep it controlled.
  • Gluten development How two wheat proteins become the elastic network that holds bread together.
  • How heat sets protein Why an egg becomes solid, fish flakes, and meat goes from translucent to opaque.
  • Smoke point The temperature at which a fat starts to break down visibly, and why it matters less than it is said to.
  • Starch gelatinisation The swelling and bursting of starch granules in hot water, which thickens sauces and cooks grains.