Coffee roasting: the changes happening into coffee beans in order to release their unmistakable aroma
Scritto alle 17:10 da Stefano Urso in: Coffee Quality,
The
coffee beans roasting process consists in introducing the green coffee beans into a machine (roaster) leading grains at a temperature between 200 and 250 ° C. The roasting time is ranging between 10 and 20 minutes, depending on the type of coffee you want to convert and the final result you want to obtain
The coffee beans, through the gradual transfer of heat, start generating over 600 different chemical substances (already at 160° C the chemical reactions start producing a physical interaction between proteins and sugars for donating us the origin of aroma). The main changes that the coffee beans have during the roasting process are: the loss of weight (about a 15-20%) due to evaporation of water and some volatile substances, the increase in volume compared with the raw green coffee, the formation of a blackish-brown color due to the carbonization of cellulose, the appearance on the surface of the grains of a brownish oil that determines the characteristic aroma, and finally a slight loss of caffeine due to heat.
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