What happens during the coffee roasting process?
Green coffee changes drastically during the roasting process. When you roast coffee, moisture is forced out of the bean, causing it to dry and expand.
During the process, some of the natural sugars are converted into CO2 gas while others are caramelised into some of the flavours that help form the complex flavours in the coffee. When the process is complete, the green bean will transform into a brown bean that is about 18% lighter while being 50 to 100% larger.
As soon as the roasting process is complete, the coffee begins to “degas,” and in as little as a week or two, the roasted coffee will have already begun to lose some of its flavour and aromas.