Coffee Roasting Chemistry
How heat transforms green coffee through drying, browning, gas formation, first crack and continued development.
Heating the bean
Roasting raises bean temperature and drives off moisture. Physical expansion, pressure and chemical transformation occur together.
Browning
As temperature and moisture conditions change, Maillard reactions and related processes contribute to brown colour and complex aroma formation.
First crack
Steam and gas pressure contribute to structural changes that can produce the audible first crack. Crack timing is useful to roasters but is not a universal chemical boundary with one fixed temperature.
Development and dark roasting
Continuing the roast increases thermal transformation. Some compounds break down or volatilise, while darker roasting can increase carbonisation and smoky/bitter character.
Continue exploring
Green coffee
Follow coffee from plant and cherry through processing, drying, milling and storage.
Green coffee →Coffee chemistry
Explore the compounds and reactions that shape roasted coffee.
Coffee chemistry →Coffee extraction
Connect grind, water, temperature, time, concentration and extraction.
Coffee extraction →Coffee Knowledge presents technical subjects as an educational reference. Terminology, grading systems and production practices can vary by country, producer, equipment and commercial context.