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What is Coffee Roast Profile

This article will help you understand what a coffee roast profile is and why you need to select special coffee roast profile for each coffee variety.
The degree of roast is generally its color. But even with the same color of roast, coffee may taste completely different. The main reason for this – different coffee roast profiles which are much more complex part of the roasting process.

Generally, it is a kind of "recipe" according to which coffee is roasted, but roaster controls processes instead of ingredients. This article will help you understand in details what a coffee roast profile is and why you need to select special coffee roast profile for each coffee variety.

How coffee roasting works

During the roasting process, there are numerous chemical reactions that take place in it. Resulted complex volatile compounds form the flavor and aroma of coffee. Different compounds are formed at different temperatures and roasting stages. So, by controlling these stages, roaster can adjust the taste of coffee.

Roasters must see what is happening with the coffee beans, so they use two temperature sensors, each of which displays two curves on the screen: temperature and its rate of change. One of the sensors is installed so that it reads the temperature of the beans, and the second records only the temperature of the air that goes out of the drum.

This allows roasters to control the whole process with high accuracy. They can influence roasting by the amount of energy applied to the beans, by the speed of the air flow that removes heat from the drum, etc.
The roasting itself has several stages:

• Drying (up to 130 °C),
• Maillard reaction (from 130 °C),
• Caramelization (from 170 °C),
• Development time (from the moment of "crack" to the end of the roast).

Together, these steps add up to a total roasting time of 8 to 14 minutes. Inexpensive commercial varieties often roast longer, but good coffee isn’t usually roasted longer than 14 minutes.

What is coffee taste made of?

Coffee taste is always a compromise between two parts. The first part (“enzymatic”) is what the bean got by genetics, processing, etc. It includes berry, fruit, flower and other descriptors. The second part belongs to the group of “caramelization of sugars” (formed from the moment of “crack” until the end of roasting). These are notes of chocolate, caramel, etc. It turns out that roasters can regulate in which direction to drag the taste more - into the “enzymatic” part or into “caramelization”.

What is the "development time" of coffee

During roasting, evaporating moisture and carbon dioxide, formed from ongoing reactions, try to get out of the bean, but partially rest against the cell walls. The pressure is increasing, and as a result, the bean cracks with a jerky sound. This moment is a "crack".

It is extremely important to fix its beginning on the chart. The time from the "crack" to the discharge of coffee is called the development time. In order for the coffee flavor to develop, the development time should be from 15% of the total roast time for a filter and from 20% for espresso.

There are two cracks during roasting process. The first one occurs at temperatures up to 200 °C, mainly due to evaporating moisture, the second one usually occurs after 220 °C, due to the burning of sugars and cell walls. Coffee roasted to the second crack is very dark with oil coming out on the surface.

How to control coffee flavor during roasting

If you look at the graph, then the upper temperature (red) curve just displays the amount of energy applied to the grains - it shows the temperature of the air leaving the drum. But why the speed of the air flow should be regulated?

Roasting coffee is a combination of 3 types of energy – conduction (beans touching hot metal), convection (hot air), and radiation (thermal radiation from metal). The distribution of these energies depends on the type and model of the roaster, but the airflow rate is also one way to change it. The higher the flow velocity, the higher the convection and the lower the conduction, and vice versa.

In addition to energy distribution, there is another important function of air. If we want to get the “enzyme” component out of the beans, then in the first half of the roast, we need to make sure that the moisture in the beans remains as long as possible, that is, the air flow rate is minimal, otherwise the fast draft will dry the coffee faster.

You can also add additional variables: such bean characteristics as density and moisture, processing method, bean size, year and month of harvest.

Coffee beans from Mr. Viet are expertly roasted in Dalat region, Vietnam. We carefully select and controll coffee roasting profile in order to get tasty and balanced coffee. We prepare it in accordance with all the traditions of Vietnam. Follow us to learn more about coffee and Vietnamese coffee culture!

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