Why does toast taste different from bread?
Heating lets certain sugars react with amino groups in bread, producing new aroma and flavor compounds. This branching chemistry is known as the Maillard reaction.
- The scientific idea
- Maillard reaction
- Fields of science
- Chemistry
How it works
Toast has flavors that the original slice of bread did not have. Heating allows its ingredients to react, creating new molecules; some escape into the air and reach your nose. The same family of reactions contributes to the character of roasted coffee and browned meat, although different starting ingredients produce different mixtures.
Look closer
The name suggests a single transformation, but the chemistry branches into many pathways. That helps explain why a coffee bean and a bread crust can both brown without tasting alike. Caramelization is a separate process involving sugars and does not require amino groups. Both can happen in one food, so brown color alone cannot tell you which reaction produced it.