What You Need to Know
A 0.5–1.0 % sodium hydroxide solution briefly immerses the dough, raising surface pH to ≈12.5–13. This alkaline environment deprotonates amino groups, enabling the Maillard reaction with reducing sugars at 220 °C. The resulting melanoidins give the characteristic dark crust and chewy crumb while the high temperature also drives caramelization of surface sugars.
The Science
Primary Reaction
Maillard browning and caramelization of crust due to alkaline surface