What Every Barista Should Know: Coffee Roasting
One of the aspects that determine whether it is really a Specialty Coffee is the roasting or roasting process. We can develop the flavor by roasting the coffee.
But how do you get the best flavor out of this coffee?
This is basically composed of 3 phases:
The Roasting Process
Also known as dehydration, in the first phase the grain loses moisture and begins to gain temperature; then comes the stage of roasting itself, in which the different chemical and physical reactions take place. And finally, the cooling stage, in which the objective is to stop these reactions once the desired roast has been obtained.
In the first stage there are changes such as the color of the grains, from a bright green to a pale yellow due to dehydration, since the water content decreases from 90 to 70%, and sensually we perceive a bread and cereal-like aroma.
At 160 ºC, poriolysis reactions begin (it is the chemical decomposition of organic matter caused by heating at high temperatures in the absence of oxygen). Its onset is indicated by a click, which is caused by the evaporation of water within the grain, which increases the internal pressure of the grain. At that time the grain cracks from its center.
The grains turn pale yellow in color and increase in size, which causes the film that covers them to detach.
Within the cells of the bean we find some polysaccharides soluble in water, which in the roasting process caramelize, causing the color change of the bean from yellow to brown and contribute to the aromatic qualities of the coffee. It is important to carry out this process with the appropriate speed since otherwise, the astringency will be greater, since the acid reactions, which contributes to increasing acidity.
Subsequently, a second click will be heard, caused by the breakdown of the grain structure giving a shiny appearance. If roasting continues for a long time, the starches and sugars that caramelized after the first snap begin to char, producing the characteristic burn of dark roasts.
Once the desired degree of browning is reached, the process must be stopped with either cold air or water. If it is carried out by the second option, the amount of water used for it is critical, since coffee tends to gain weight because it absorbs water. The entire roasting process can take anywhere from 7 to 30 minutes depending on the type of roaster.
During the roasting process, the temperatures reached by the coffee beans are around 193ºC for a light roast, close to 200ºC for a medium roast, and close to 218ºC for a dark roast. Once the roasting process is finished, the beans go to trays to cool quickly and thus stop the process when desired.
In order to highlight and be able to enjoy more of the characteristics of smoothness, aroma and citric acidity of our varieties, at Porte we have determined that the amount of beans to be roasted must be 12kg per batch and that the most suitable point is Medium.
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