Maillard reaction

The Maillard reaction is a set of chemical reactions between proteins and sugars that happens when food is heated. It turns surfaces brown and creates hundreds of new flavor and aroma compounds: the savory crust on a steak, the crust of bread, toasted nuts, roasted coffee and fried onions. It is named after the French chemist Louis-Camille Maillard, who described it in the early 1900s.

How to do it

1. Dry the surface. Pat meat and vegetables dry, or let them air-dry in the fridge. Water keeps the surface near 100°C (212°F), too cool for fast browning.
2. Use high heat. Browning is quick above about 140°C (285°F). Sear in a hot pan, roast at 200°C (400°F) or more, or broil.
3. Do not crowd the pan. Crowded food steams instead of browning.
4. Leave food still long enough to form a crust before turning it.

How to tell it is done

The surface is a deep golden brown and smells roasted, nutty and savory. Food often releases easily from the pan once a crust forms.

Why it works

Heat makes amino acids from proteins react with certain sugars. These reactions build brown pigments and many flavor compounds. Different foods have different proteins and sugars, so seared beef, toast and chocolate all taste different. A slightly alkaline surface browns faster, which is why pretzels are dipped in an alkaline bath and some recipes add a pinch of baking soda to onions.

It is different from caramelization, which needs only sugar and higher temperatures.

Common mistakes

• Putting wet meat in the pan, which gives gray, steamed meat.
• Using a pan that is not hot enough.
• Moving food too often.
• Going too far. Past brown comes black, which tastes bitter and burnt.

In recipes

"Brown the meat", "sear until a crust forms" and "toast until golden" all ask for the Maillard reaction. The browned bits left in a pan are called the fond.