Maillard Reaction¶

title: "Maillard Reaction" tags: [coffee/roasting] status: Draft aliases: [] related: []

The Maillard reaction is a chemical reaction between amino acids and reducing sugars that occurs when food is heated, producing complex flavours, aromas, and browning.

In coffee roasting, the Maillard reaction begins after the beans have dried and as temperatures rise. It is responsible for many of the desirable flavours in coffee, including notes of toast, nuts, chocolate, caramel, and malt. Unlike simple burning, the Maillard reaction creates hundreds of new flavour and aroma compounds through a series of heat-driven reactions.

In practical terms, how long coffee spends in the Maillard phase strongly influences balance and sweetness. Too little time can result in sharp, underdeveloped flavours, while too much time can mute acidity and lead to dull or baked tastes.

In coffee roasting, the Maillard reaction typically begins at approximately 140 °C to 160 °C (285 °F to 320 °F) inside the coffee bean and continues as temperatures rise toward First Crack.

Practical context

Below ~140 °C: The roast is primarily in the drying phase, where free moisture is being driven off and little flavour development occurs.
~140–160 °C: The Maillard reaction starts. Amino acids and sugars begin reacting, creating browning and foundational flavour compounds.
~160–190 °C: Maillard reactions intensify, contributing sweetness, body, and complex aromas.
~195–205 °C: First crack typically occurs, marking the transition from Maillard-dominated reactions to development and caramelisation.

Important note for home roasters
These temperatures are bean temperatures, not air or drum temperatures. Actual readings vary by roaster design and probe placement, so it is best to use these ranges as guidelines rather than fixed targets.