The Maillard reaction occurs as food is cooked. ... During the cooking process, amino acids and certain simple sugars in the food form new molecules, which join together in chains. These groups of molecules reflect light in such a way that we then perceive the surface of the food as being brown.

What causes the Maillard reaction?

In a Maillard reaction, the reactive carbonyl group of a reducing sugar molecule reacts with the nucleophilic group of an amino acid, causing a change in color (usually darkening of color) and flavor of a food product. Heat (energy) is usually required for a Maillard reaction to proceed.

When can Maillard reaction occur?

The Maillard reaction occurs when dry food is cooked at a high heat or for a long period of time. The reaction starts slowly at 250°F (121°C) and ramps up quickly as the meat fibers hit 350°F (177°C). However, the Maillard reaction only happens in foods where both sugar and protein are present.