There are many ways that coffee roasters work in order to flavor the coffee beans. Many coffee buyers aren’t aware that the type of the bean used has a big part in the flavor of how it tastes after being roasted. The flavors of various beans have a lot to do with where the bean was grown, but how the bean was roasted also plays a part.
There are over 800 different compounds in coffee beans. These compounds contribute heavily to the flavor of the bean. Often other flavors are added to the bean to make it more appealing. These flavors are usually added after the beans are roasted, but before the coffee is ground.
The characteristic flavor of coffee comes from roasting. Coffee beans are actually green before they are roasting. Roasting causes the green bean to expand and change color, flavor, scent, and since the roasting gets rid of moisture in the bean, the density also changes. As a bean is roasted it goes from a pale green color to yellow, where it makes a gradual change into shades of brown. The roasting of the beans changes the flavor. The flavor from a bean that has roasted for longer amounts of time usually taste so different from when it is fresh that even many coffee connoisseurs are unable to tell which kind of bean it was.
Roasting coffee is actually a chemical process. In this process, the flavor of the bean is altered so much that it augments the flavor. Beans that been roasted in such a way that the sweetness and aroma are maximized and the bitterness and acidity are minimized are highly desirable for espresso. Beans contain sucrose. As the sucrose is roasted, the bean darkens. This is because of the caramelization process as sucrose is sugar. When the temperature of the beans in the roaster reach temperatures of between 170-200°C, this is the moment when the sugars caramelize and bring out the wonderful flavor of the coffee.