Specialty Coffee Bean Terminology Explained

If you’ve ever wondered what ‘natural process’ means or why Agtron 50 is important, you’re not alone. Specialty coffee uses dozens of technical terms that can confuse anyone trying to understand more about their beans. From roast level numbers to defect types and processing methods, knowing these terms helps you make better buying and brewing decisions.

Here’s a clear guide to the most common specialty coffee bean terms — including exact numbers like Agtron 50, roast scales from 100 to 25, and types of defects — explained in plain English for coffee drinkers who want precision, not fluff.

Roast Level: The Agtron Scale

In the U.S., a common way to measure roast degree is the Agtron scale, ranging from 100 (lightest) to 25 (darkest). This numerical system reflects color values measured using a device called the Agtron M-Basic, a specialized spectrophotometer. A mid-range roast is often around Agtron 50, a widely referenced benchmark in the industry.

Coffee Species: The Big Three

There are three main coffee species: Arabica, Robusta, and Liberica. Arabica, originating in Ethiopia, is considered the highest quality of the three and is predominantly grown at higher altitudes. Its flavor profile is generally more nuanced and delicate compared to the harsher, more bitter Robusta, which has about twice the caffeine content.

Coffee Processing Methods

How coffee is processed after harvest dramatically affects its flavor:

• Washed : Uses water to remove the coffee cherry’s pulp, resulting in cleaner, brighter cups with fewer defects.
• Natural : Also called dry processing, where coffee cherries are dried whole. Produces fruitier, fuller-bodied flavors but carries a higher risk of defects.
• Honey / Pulped Natural: A hybrid method where some mucilage remains on the bean, adding sweetness and body. Not named directly in the original text but related to natural-style processes.

Defects in Green Coffee Beans

Defective beans can ruin a batch. Key types include:

• Unripe beans : Green in color, these taste grassy and unpleasant.
• Quakers: Under-ripe or under-roasted beans that remain pale and taste starchy.
• Black beans, moldy beans, fermented beans, insect-damaged beans: All fall under the umbrella of ‘defects’ that lower cup quality.

Professional cuppers and roasters remove these by hand before roasting. Leaving them in will create off-flavors in the brewed coffee.

Other Key Terms in Coffee Production

• Storage / Aging : Holding green beans in climate-controlled warehouses to balance moisture or mellow flavors. Can reduce acidity and aroma, according to trade opinions.
• Vintage / Old Crop : Coffee beans over two years post-harvest, drier than fresh crop or past crop (next year’s beans).
• Caffeine Content: Varies by species — Arabica ~1%, Robusta ~2%, instant coffee ~3–6%.
• Cup of Excellence (COE): A prestigious competition and auction platform for top-quality coffees, founded in Brazil in 1999, now held in countries like Guatemala, Panama, and Nicaragua.
• Screen Size / Sieve : Green beans are sorted by size using mesh screens measured in 1/64-inch units. A No. 18 sieve keeps beans larger than 18/64 inch; higher numbers mean bigger beans.

Historical and Environmental Factors

• Frost Damage : Devastating to coffee farms, like the 1975–76 Brazilian frost that wiped out 915 million trees, slashed production from 25 million to 8.2 million bags, and caused prices to spike from $0.60 to $3.36 per pound.
• Leaf Rust : A fungal disease affecting coffee leaves in rainy regions, once destroyed Sri Lanka’s Arabica industry, leading to a shift to disease-resistant Robusta.

Shade-Grown Coffee and Altitude

Shade trees, such as banana or mango, are planted among coffee to protect against direct sun, frost, and pests. High-altitude growing improves cup quality, especially for Arabica, by slowing bean development and increasing sugar accumulation.

Specialty Coffee: What It Means

‘Specialty coffee’ lacks a strict global definition, but it generally refers to beans with distinct, memorable flavors and high quality. The term covers both classic high-rated coffees and newer standouts recognized by local and international specialty associations.

Experimental and Multiple Roast Methods

• Double Roast : Roasting beans twice, often to even out inconsistencies. Can improve appearance but often flattens flavor complexity.
• Coffee Futures Classification : The New York futures market classifies coffees into four types, including Colombian, Kenyan, Tanzanian (all washed), along with non-washed Arabica and Robusta.

This system influences global trade pricing and quality expectations.

Frequently Asked Questions

What is the Agtron scale and what does Agtron 50 mean?

The Agtron scale measures coffee roast color, ranging from 100 (very light) to 25 (very dark). Agtron 50 is considered a mid-range roast, often used as a general industry benchmark for balanced roast color and flavor development.

What are the main coffee species?

The three primary coffee species are Arabica, Robusta, and Liberica. Arabica, originating from Ethiopia, is known for higher quality and is typically grown at altitude. Robusta is more bitter, higher in caffeine, and more disease-resistant, while Liberica is rare and has a unique flavor profile.

What are the main coffee processing methods?

The three main processing methods are washed (removing the cherry pulp with water), natural (drying the whole cherry), and honey/pulped natural (leaving some fruit mucilage on the bean). Each affects flavor, body, and cleanliness differently.

What are common coffee bean defects?

Common defects include unripe (green) beans, black beans, moldy beans, insect-damaged beans, quakers, and fermented beans. These lower cup quality and should be removed before roasting.

What is Cup of Excellence (COE)?

Cup of Excellence is an annual competition and auction for top-quality specialty coffees, first held in Brazil in 1999. It’s now hosted in countries like Guatemala, Panama, and Nicaragua, and winners are sold via international auctions.

What does screen size mean in coffee?

Screen size refers to the physical diameter of green coffee beans, sorted using mesh sieves measured in 1/64-inch units. A No. 18 sieve retains beans larger than 18/64 inch; higher sieve numbers indicate larger beans.

Recommended FrontStreet Beans for Learning Coffee Terminology

Explore key coffee terms through taste: try FrontStreet’s Brazil Yirgacheffe-region-inspired Gedeb (Gedeb) washed coffee for bright citrus and floral notes; their Colombia Sidra from Huila shows complex fruitiness from double anaerobic fermentation; and their Panama Geisha from Boquete highlights the premium qualities often discussed in specialty coffee. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.