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The science of roasting coffee beans

After the sourcing of high quality coffee beans, the most important phase in the production of high quality coffee begins, which is the roasting and blending of the beans.

A good roaster needs to be both an artist and a scientist to maintain the quality and consistency of the beans. During the roasting process, the sugars and other carbohydrates in the coffee beans caramelise to produce a substance known as coffee oil. The two most typical roasting methods are drum roasting and hot air roasting.

Coffee bean roasting process

Drum-type machines roast coffee beans as they rotate in a rotating drum heated by gas or wood. Once the beans are roasted, they are poured into a cooling vessel to avoid excessive scorching of the beans. The hot air roaster roasts the coffee beans as they move around in the hot air. Most green coffee is roasted at around 200 degrees. Roasting swells the coffee beans and they increase in size by more than 50%, but at the same time they lose much of their weight.


Which toast to choose?

Lightly roasted beans can range in colour from cinnamon to chocolate. Lighter roasts are not usually used for espresso, as they produce a sharper, more acidic taste than darker roasts. Darker roasts, on the other hand, have a richer flavour and can even have a strong sweet and sour taste. The amount of oil on the surface of the coffee bean increases the roasting time accordingly.

As the roast gets darker, the acidity and the amount of caffeine decrease proportionally. With more than 100 coffee growing regions in the world, each producing beans with different characteristics, we believe that a balance of flavours is essential for a quality espresso, and the right blending of beans is crucial to achieve this. A single variety of coffee beans does not usually have all the different characteristics needed to produce a delicious espresso.

Many espresso coffee brands contain three to seven different types of coffee beans. An experienced roaster, who knows all his coffee varieties, masterfully blends different types of beans to get the coffee with the desired flavour. The roaster usually keeps his knowledge a closely guarded secret.