Coffee roasting is the process all green coffee beans go through before they can be used to make coffee.
The roasting process itself changes the colour of the green coffee beans. First they turn yellow, then brown. The longer they roast the darker they become. The strongest roasts result in black beans. At the same time, the heat causes changes in the taste and smell of the beans, and aromatic oils are released that bring out the flavour of coffee.
The Science of Coffee RoastingRoasting is a critical part of coffee production as it develops and brings out the full flavour and aroma of the bean. Proper roasting requires the right temperature and the right length of roasting time.
In the nineteenth century, people carefully roasted their coffee at home on their stoves or over open fires. Now, with the growth of the coffee industry, coffee roasting has become the job of commercial coffee roasters who use enormous ovens to roast the coffee in vast quantities.
It can take just a minute to achieve the ideal roast. Roast the coffee beans for too long and you get a roast that is too dark and too bitter. As a result, temperatures and time are monitored closely and carefully controlled – sometimes even by computer - as even just a few seconds can dramatically change the final flavour of the coffee.
In general, a light roast gives a mild taste; a medium roast produces a well– rounded, rich flavour and aroma, and a high roast gives a strong, distinctive flavour.
Different varieties of beans require different levels of roasting. For instance, in order to preserve the original characteristics of Arabica beans, they should not be roasted too dark.