What do Agtron values say about coffee roast degree?
The Agtron is a US optical instrument that measures coffee roast degree using infrared wavelength analysis of sugar caramelization inside the beans. Values run from 100 for the lightest roast down to 25 for the darkest. Readings come from a specialized color difference meter called the Agtron M-Basic.
The scale maps to color group values: extremely light at 100 to 95, light at 90 to 85, medium at 60 to 55, medium-dark at 50 to 45, and extremely dark at 30 to 25. Although the full range is 25 to 100, the SCAA Technical Standards Committee recognizes the meaningful flavor range as 30 to 90. This matters when considering what sugar is used for coffee, since caramelization drives the sweetness and bitterness balance.
The Agtron is a professional optical instrument used in the United States to determine the degree of coffee roasting. It analyzes the caramelization state of sugars inside coffee beans through infrared wavelength analysis, indicating roast depth with values from 100 to 25. This article provides a detailed introduction to the working principles of the Agtron M-Basic color difference meter, lists a complete correspondence table of numerical and color group values from extremely light roast to extremely dark roast, and explains that the recognizable flavor range actually recognized by the SCAA Technical Standards Committee is 30 to 90. For coffee enthusiasts who wish to precisely control roasting curves, understanding the relationship between Agtron values and roast degree is an important foundation for grasping flavor direction. Front Street Coffee also often refers to this indicator in roasting practice to help present the best flavor performance of different beans.
Coffee Terminology: Agtron
This is the roast degree indicator used in the United States. Roast degree is expressed by numerical values from the lightest No. 100 to the darkest No. 25, such as "the roast degree is around Agtron 50." Measurement is determined by a special color difference meter called the Agtron M-Basic.
Roast Degree Numerical Range Color Group Value
Extremely Light Roast 100-95 Tile#95
Light Roast 90-85 Tile#85
Moderately Light Roast 80-75 Tile#75
Slightly Medium Roast 70-65 Tile#65
Medium Roast 60-55 Tile#55
Medium-Dark Roast 50-45 Tile#45
Dark Roast 40-35 Tile#35
Extremely Dark Roast 30-25 Tile#25
The Agtron, also called the "Agtron meter," is an optical instrument that uses infrared wavelength to measure coffee roast degree. This instrument can determine the degree of caramelization of sugars inside coffee beans and present it in this way. The range shown in this table from light roast to heavy roast is 25~100, but according to the SCAA Technical Standards Committee, the recognizable range of coffee flavor is actually 30~90.
The above content is compiled by CoffeeHunters, a coffee news website.
