Maillard reaction - is a form of nonenzymatic browning. It results from a chemical reaction between an amino acid and a reducing sugar, usually requiring heat. It is vitally important in the preparation or presentation of many types of food.
This is the Maillard Reaction. It is what happens when meat is browned. This reaction is a must-have in the cooking of all meats because it adds flavor, texture and color, which are three of the seven main components when plating a dish.