Why do some foods brown when cooked at high heat?

When foods are cooked at high heat, two main reactions cause browning. The Maillard reaction occurs when amino acids and reducing sugars interact at temperatures above roughly 280°F (140°C), producing hundreds of new flavor and aroma compounds along with brown pigments called melanoidins. This is responsible for the crust on bread, seared meat, and roasted coffee. Caramelization is a separate process where sugars alone break down and polymerize at high temperatures, typically above 320°F (160°C), creating brown colors and complex sweet, nutty flavors. Both reactions are accelerated by dry heat and low moisture, which is why boiling food rarely produces browning while roasting, frying, and grilling do.