Coffee beans are only matured coffee cherry seeds, which are processed and dried into coffee beans. These beans are green in color before roasting and have a grassy and beanie fragrance. This smell you get is not given by the unroasted coffee beans but by the 800 and 1000 different aroma compounds developed during the coffee roasting process, which make the flavor of the coffee. Coffee roasting can be performed in different ways and techniques that affect the taste, which is necessary to know if you want to become an operator coffee dealer. You can also do roast profiling to enhance the performance of the aroma compounds and determine what taste it will offer.
To become an Operator Coffee dealer, you should know the roasting stages so that you can easily identify the coffee beans for the degree of their roast.
Since coffee beans have an 8-12% humidity, they must be dried before roasting. Drying can last 4-8 minutes in a traditional drum roaster at 160 degrees Celsius. But with drum roasters, utmost care must be taken to avoid burning the beans by supplying too much heat initially. This stage is also important for the beans to collect energy since the roasting stage is exothermic.
At 160 degrees Celsius, the beans produce a peculiar smell, like toasted bread and hay. This stage is called the browning stage when the aroma precursors convert into aroma compounds. The reaction is called the Maillard reaction, in which the reducing sugars and amino acids react to create different aromas and color compounds known as melanoids. At the browning stage, the roasting naturally slows down, which ensures flavor development, at the end of which the coffee beans start to pop, which is called the first crack, from where the development stage starts.
Development Or Roasting Stage
At the beginning of this stage, the reaction becomes exothermic, and the coffee beans start to crack and explode due to the energy collected during the drying and browning stages. The aroma compounds begin to develop during the development stage, due to which the roast should be slowed down to get a smoky taste and sharp flavor. Depending on the desired flavor profile and roast degree, the time taken by the development stage makes up almost 15-25% of the total roast time.
The roast degree can be measured by the color meter or simply by tasting. The roast degree decides the coffee’s flavor. Lightly roasted coffee beans are more acidic, and fruity flavors are common due to the high amounts of 5-hydroxymethylfurfural, which breaks down to less fruity compounds with further roasting leads to an increase in the sulfuric compounds. Hence, dark roasted beans are bitter and have roasty, burnt flavors.
The total roast time and the time length of each stage are important factors in determining the flavors of the coffee. Fast roasting will give more desired aroma compounds, but it should not burn the beans. This is because quick roasting increases the number of aroma compounds created at the beginning of the development stage.
These are the basics of coffee roasting that operator coffee dealers should know about so that they are well informed about the degree of roast that they should provide.