The Agtron scale is a color measurement system used to evaluate roasted coffee beans.
In the 1970s, the Specialty Coffee Association of Americans (SCAA) developed together with Agtron Inc. (an American instrumentation company) a classification system made up of 8 colored discs that establish the degree of roasting of the coffee, with numbers varying between 25 and 95 (#25 / #35 / #45 / #55 / #65 / #75 / #85 / #95), with 95 being very light and 25 being very dark.
It is worth noting that although the Agtron scale is a useful tool for measuring the degree of roasting of coffee beans, it does not provide information about the flavor, aroma or overall quality of the coffee.
To evaluate these factors, coffee professionals generally use “cupping”, a standardized tasting method.
In general, considering the same batch of high quality coffee, it can be said that the physical and sensorial properties expected with different roasting points are:
Light Roast
Light roast coffee has a light brown color and a matte surface.
This roasting tends to preserve more of the original flavors and aromas of the coffee bean, however, resulting in a more acidic cup, with floral or fruity aroma and flavor notes.
The body is generally lower, and the coffee has a clean finish.
The greater acidity of coffee is not always appreciated by consumers, who often find it strange when they taste it in a cup.
The Agtron scale for light roast coffee ranges from 95 to 75 .
Medium Roast
Medium roast coffee has a medium brown color and a matte to slightly shiny surface.
This roast balances acidity and bitterness, producing a rounded flavor with notes of chocolate, nuts, caramel and vanilla.
The body is generally larger than that of light roasts, and the coffee has a greater balance between acidity, sweetness and body.
In the specialty coffee market, filtered preparation methods widely use medium roast coffees.
The Agtron scale for medium roast coffee ranges from 65 to 55 .
Dark Roast
Dark roast coffee has a dark brown color and a shiny to oily surface.
This roast has an intense flavor, with notes of dark chocolate, roasted nuts and caramelized sugars.
However, when too dark, unpleasant burnt and rancid flavors may appear.
The body is generally smaller than that of a medium roast, with lower acidity.
It is generally believed that espresso coffee requires a darker roast, but this is not always true.
The Agtron scale for dark roast coffee ranges from 45 to 25.
This analysis can be done in two ways:
It can be done manually, where it is analyzed by specialized professionals as follows:
1-The coffee must be finely ground, corresponding to the grind for espresso. Very fine (talc) is not recommended because the powder absorbs moisture from the air, which changes its color.
2- Compact the powder to make its surface uniform for light reflection.
3-The powder should be as close to the edge of the container used. The closer to the surface, the better the color visualization.
4- Carry out the comparative visualization in a well-lit place, preferably with natural light. But it can also be done with artificial light that guarantees at least 400 lumens on the surface of the color scale.
Or use professional precision instruments to measure the degree of coffee roasting, such as the one in the photo to the side, which you can have at home and analyze your own beans. These equipment are suitable for both whole coffee beans and ground coffee. They have integrated optical technology that analyzes the Agtron number, as it is called, through the reflectance obtained in the infrared band and is correlated to the caramelization of sucrose. The lighter the roast, the greater the reflectance.
It is important to use ground grain when using the discs to compare. This equipment allows professional coffee roasters to accurately measure the Agtron roast degree and roast degree name.
Now it's easier for you to analyze the coffee you're drinking at home. Do you have a coffee roast analyzer at home? Leave your opinion.
