Agtron Values vs Coffee Bean Roast Levels: Understanding Coffee Bean Pink Color Values and Surface Color Values

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Many coffee shops that roast their own coffee beans display, in addition to information about coffee origin, growing altitude, coffee variety, processing method, and flavor profile, two numerical values on their coffee bean introduction cards or packaging: one is the Agtron bean surface color value, and the other is the Agtron ground color value. So what do these two values indicate? In this article, FrontStreet Coffee will explain what the bean surface color value and ground color value are.

What is Agtron?

The Caramelization Analyzer (Agtron) is an optical instrument that uses infrared wavelengths to measure coffee roast degree. This instrument can determine the degree of sugar caramelization both externally and internally within coffee beans and present this information in a numerical format. Different countries have varying perspectives on coffee roasting, lacking uniformity. When coffee roasting first became popular, disagreements emerged between different roasting schools of thought.

As one of the authoritative representatives in the coffee world, the Specialty Coffee Association of America (SCAA), to resolve these disagreements, collaborated with Agtron Company to use infrared wavelengths to measure coffee caramelization and detect the degree of coffee bean caramelization. They divided colors from light to dark into eight equal parts, creating eight standard color tiles to serve as roasting standards for the coffee industry, allowing roasting masters from different schools to communicate on the same "channel."

How Do Agtron Values Define Coffee Bean Roast Degrees?

Agtron Value #95: Light Roast
Drop time: As first crack becomes dense and approaches its end

Agtron Value #85: Cinnamon Roast
Drop time: Around the end of first crack

Agtron Value #75: Medium Roast
Drop time: After first crack ends

Agtron Value #65: High Roast
Drop time: The quiet period between first and second crack

Agtron Value #55: City Roast
Drop time: At the beginning of second crack

Agtron Value #45: Full City Roast
Drop time: Before second crack becomes dense

Agtron Value #35: French Roast
Drop time: When second crack becomes dense

Agtron Value #25: Italian Roast
Drop time: When oils begin to surface on the beans

FrontStreet Coffee has roughly organized the above eight major regions. We can categorize roast degrees into light roasts (including light roast & cinnamon roast), medium roasts (including medium roast & high roast), medium-dark roasts (including city roast & full city roast), and dark roasts (French roast & Italian roast).

Among the more than 50 coffee beans offered by FrontStreet Coffee, over 70% are primarily light-roasted, including coffee beans from regions such as Ethiopia, Kenya, Guatemala, Colombia, Panama, Costa Rica, Honduras, Tanzania, Bolivia, and China's Yunnan, all using cinnamon roast. The remaining 30% of coffee beans, including those from Brazil, Indonesia, Hawaii Kona, Jamaica Blue Mountain, Papua New Guinea, Mexico, and espresso blend coffee beans, use medium roast.

What Are Bean Surface Color Values and Ground Color Values?

The bean surface color value refers to the infrared caramelization measurement performed on whole coffee beans after roasting completion, judging the degree of surface roasting from the coffee bean's exterior. However, the surface roast degree cannot determine whether the entire coffee bean has achieved consistent roasting throughout. It's possible that excessive heat during the roasting process caused severe surface caramelization while the bean's interior didn't reach the corresponding standard value. Therefore, the Agtron value standard is based on the caramelization value of coffee beans after grinding (i.e., the ground color value).

The ground color value, as the name suggests, is the color value of the coffee bean's core after grinding. Only when the bean core's color value reaches the Agtron numerical standard can we say that the roasted beans have achieved the corresponding degree. This is because only when the bean surface and core are uniformly caramelized internally and externally will the brewed coffee's flavor remain stable. If only the surface is caramelized while the core hasn't been uniformly caramelized, it will result in both bitter and astringent coffee flavors, indicating that this roast has "failed."

Does Roast Degree Affect Acidity in Coffee Beans?

When customers ask FrontStreet Coffee about coffee beans with pronounced acidity, FrontStreet Coffee's baristas will recommend cinnamon-roasted Kenyan coffee beans or Ethiopian coffee beans. When customers ask about coffee beans without acidity, FrontStreet Coffee's baristas will recommend medium-roasted Brazilian coffee beans or Indonesian coffee beans.

Why is this? The roast degree of coffee affects its acidity to some extent - the darker the roast, the less acidic the coffee. This is because during the roasting process, caramelization gradually produces bitter substances, such as chlorogenic acid lactones and phenylindanes. As the roast degree becomes darker, these byproducts increase, especially after entering second crack. Therefore, friends who enjoy acidic coffee can choose light-roasted coffee beans, while those who prefer rich, full-bodied sensations can choose medium-roast or darker coffee beans.

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Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473