Maillard

Louis-Camille Maillard was a French physician and chemist who in 1912 published a paper describing what happened when he heated amino acids (proteins) with reducing sugars: they produced brown compounds with complex flavors and aromas. He was studying the synthesis of proteins in biological systems, not cooking. The application of his reaction to the flavors of cooked food came later.

The Maillard reaction is a complex cascade of chemical reactions that begins when amino acids and reducing sugars are exposed to heat (typically above 140°C / 285°F in dry conditions). The reactions produce hundreds of different flavor and aroma compounds, as well as the brown color of a seared steak, toasted bread, roasted coffee, and the crust of bread. Without the Maillard reaction, most cooked food would taste bland.

The distinction between Maillard browning and caramelization is important: caramelization involves only sugars, while Maillard requires both proteins (amino acids) and sugars. Bread crust is Maillard; pure sugar syrup turning brown is caramelization. A steak seared in a hot pan is Maillard. The two reactions can occur simultaneously but are chemically distinct.

Maillard's name entered the cooking vocabulary largely through the food science and culinary tradition movement of the late 20th century. Writers like Harold McGee (On Food and Cooking, 1984) popularized the chemistry of cooking for a general audience. Today, serious cooks worldwide know the Maillard reaction by name and understand why a hot pan and dry surface produce better flavor than a wet, steaming one.