The Maillard reaction — named after French chemist Louis-Camille Maillard, who first described it in 1912 — is the chemical process that produces the brown colour and complex flavour of seared meat, toasted bread, roasted coffee, baked pastry, and caramelised onions. It is not one reaction but a cascade of hundreds of chemical reactions between amino acids and reducing sugars at temperatures above 140°C (280°F). The Maillard reaction produces over 600 identified flavour compounds — more than any other single chemical process in cooking. Understanding it explains why: seared steak tastes different from boiled steak, toast tastes different from bread, and roasted coffee beans smell different from green beans.
- **Temperature threshold: 140°C (280°F).** Below this temperature, the Maillard reaction does not occur at significant rates. This is why boiled meat (100°C maximum) does not brown — water caps the temperature below the Maillard threshold. To get browning, you need dry heat, fat-mediated heat, or a combination. - **Surface moisture is the enemy.** Water on the surface of meat holds the temperature at 100°C (the boiling point of water) until the water evaporates. Patting meat dry before searing is not a minor tip — it is the single most important step in achieving Maillard browning. Wet meat steams; dry meat sears. - **It is not caramelisation.** Caramelisation is the browning of sugar alone (no protein involved). The Maillard reaction requires both sugar AND amino acids (protein). A seared steak undergoes Maillard. A brûléed sugar crust undergoes caramelisation. Both produce browning, but through different chemistry. - **This is why bread crusts taste different from bread interiors.** The exterior of bread reaches Maillard temperatures (200°C+ in the oven). The interior, insulated by the dough, stays below 100°C. Same ingredients, different temperatures, different flavour.
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