Why does toast turn brown?
Show answer & explanation
Answer: Sugars caramelize and react
Bread burns from oven heat — Wrong. Toast isn't burning (that would be black and bitter). The browning is a chemical reaction called the Maillard reaction, not combustion.
Moisture evaporates out — Wrong. Moisture does evaporate making toast crispy, but the brown color comes from chemical reactions between sugars and proteins.
Sugars caramelize and react ✓ — Correct! Heat triggers the Maillard reaction—amino acids and sugars combine to create hundreds of new flavor and color compounds. This happens above 140°C (285°F). That's why toast tastes nutty and sweet—it's chemistry, not just drying!