How Does the Coffee Association of America Agtron Scale Guide Roasting?

The Specialty Coffee Association of America, often shortened to the coffee association of America, established the Agtron caramelization scale that roasters use to judge roast degree by bean color. The RoAmi roast degree analyzer embeds that Agtron algorithm in a colorimeter. Reading bean or ground color gives an Agtron value, and recording it batch after batch keeps roasting consistent and stable.

The SCAA divides roast color into eight levels from light to dark and produced eight standard color patches as an industry reference, though Japan and Taiwan instead judge roast by cracking point. The RoAmi needs about three minutes of preheating, then color-value calibration. Comparing bean color to ground color yields the Roast Delta, which indicates roast rhythm and predicts flavor performance.

In coffee roasting, how can we ensure that every batch of beans achieves consistent quality? Besides relying on cupping to evaluate flavor, we also use the RoAmi roast degree analyzer to record the Agtron caramelization values of the coffee beans and keep historical data for reference. The RoAmi is essentially a colorimeter, with SCAA's Agtron algorithm embedded internally, capable of calculating the roast value by reading the color data from the surface of the beans or ground coffee. This article will introduce how to use this device, the meaning of Agtron values, and how to calculate the Roast Delta value from the bean color value and ground color value, and interpret the guiding significance of this value for roasting rhythm and flavor performance.

RoAmi Coffee Roast Degree Analyzer

This is a device used to determine the roast degree of roasted coffee beans. In principle, the RoAmi is equivalent to a colorimeter, or can be understood as a color difference meter. Based on the colorimeter, it integrates SCAA's Agtron value algorithm internally, so when the machine reads the color data from the surface of coffee beans or ground coffee, it can calculate the corresponding roast value through internal computation.

Typically, when we receive several batches of beans roasted with different profiles, besides confirming their flavor performance through cupping, we also use this RoAmi roast degree analyzer to record their Agtron values (caramelization values) and save historical data. With the help of the device's detection, we can ensure the consistency and stability of roasting.

Agtron (Caramelization Value):

This value was established by the Specialty Coffee Association of America (SCAA) using infrared caramelization measurement technology (Agtron), determining the roast degree by measuring the color of coffee beans. In SCAA's roast degree standards, the color is divided into eight levels from light to dark, and eight standard color patches are made for the coffee industry as a reference for roast identification. However, different regions adopt different identification standards; for example, Japan and Taiwan determine the roast degree based on the cracking point of coffee beans.

Below is a brief introduction to how to use this device.

After turning it on, it takes about three minutes for preheating.

After preheating is complete, we will perform color value calibration.

Since the roast color of coffee bean samples may not be completely uniform, we generally measure three times and take the average of the three as the final result.

First, the bean color value is measured.

Next, the ground color value is measured.

By measuring the bean color value and ground color value of the beans, the Roast Delta value can be calculated.

Roast Delta Value

It refers to the "difference" between the measured Agtron value of the beans and the Agtron value of the ground coffee.

Within fifteen minutes after the beans are discharged and cooled, measure with the Agtron analyzer to obtain a value of 53.5/60.8, which means the Roast Delta value of this coffee bean is 7.3 (60.8–53.5=7.3).

So what use are these data to us?

For the same type of coffee beans with the same roast degree, the smaller the Roast Delta value, the more flat the flavor tends to be, lacking depth and dynamics; the larger the Roast Delta value, the more distinct and three-dimensional the flavor, and the richer the dynamics.

We can see the roasting rhythm of a particular bean from the Roast Delta value. A large Roast Delta value usually represents a fast roasting rhythm, a steep temperature rise curve, and a shorter total roasting time; conversely, a small Roast Delta value represents a slow roasting rhythm, a relatively gentle temperature rise curve, and a longer total roasting time.

Generally speaking, the Roast Delta value for medium to medium-dark roasted beans is between 4-10; for light roasts, it is mostly between 9-16.

The above content is compiled by CoffeeHunters, a coffee news website.