Glossary
Maillard reaction
The reaction between sugars and amino acids under heat that produces the colour and much of the flavour of kilned malt, and continues slowly in packaged beer as staling.
Pronounced my-YAR.
Also called maillard, browning reaction.
The same chemistry that browns bread crust and sears meat produces malt’s bread, biscuit, toffee and roast character during kilning. It is distinct from caramelisation, which involves sugar alone.
It does not stop at the maltings. Maillard chemistry continues extremely slowly at ambient temperature, and it is a substantial part of why beer stales — and why staling roughly doubles in rate for every 10 °C of extra warmth.
Related
- Melanoidin — The pigment class it produces.
- Kilning — Where it does most of its work.
- Staling — Where the same chemistry becomes a problem.
More vocabulary
Adjunct · Aroma hop · Base malt · Bittering hop · Black malt · Brettanomyces · Candi sugar · Chocolate malt · Crystal malt · Dextrin
See every term on the glossary index.
Last reviewed 2026-08-16.
Evidence
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The Maillard chemistry that develops malt flavour during kilning continues extremely slowly in packaged beer at ambient temperature, and is a substantial contributor to staling.
Backed by a source
Sources: Beer: Tap into the Art and Science of Brewing — print; Brewing: Science and Practice — print