Coffee Roasting

The next step in the process is the roasting of the green coffee. Coffee is usually sold in a roasted state, and with rare exceptions all coffee is roasted before it is consumed. It can be sold roasted by the supplier, or it can be home roasted.


The roasting process influences the taste of the beverage by changing the coffee bean both physically and chemically. The bean decreases in weight as moisture is lost and increases in volume, causing it to become less dense.


The density of the bean also influences the strength of the coffee and requirements for packaging.
The actual roasting begins when the temperature inside the bean reaches approximately 200 °C (392 °F), though different varieties of beans differ in moisture and density and therefore roast at different rates. During roasting, caramelization occurs as intense heat breaks down starches in the bean, changing them to simple sugars that begin to brown, changing the color of the bean.


Sucrose is rapidly lost during the roasting process and may disappear entirely in darker roasts. During roasting, aromatic oils and acids weaken, changing the flavor; at 205 °C (401 °F), other oils start to develop. One of these oils is caffeol, created at about 200 °C (392 °F), which is largely responsible for coffee's aroma and flavor.