Beginner’s Guide to Common Coffee Terms Explained

If you're new to coffee, terms like 'Arabica,' 'Agtron,' or 'washed process' can sound like industry jargon. Understanding these basics helps you communicate better with baristas, choose beans with confidence, and appreciate the craft behind your cup.

Here’s a clear breakdown of 20 essential coffee terms every beginner should know—from roast levels to processing methods and common defects—with exact numbers, ratios, and technical details preserved.

Coffee Roast Levels & Measurement

In the U.S., roast degree is measured using the Agtron system, ranging from 100 (lightest) to 25 (darkest). The standard reference tool is the Agtron M-Basic colorimeter, with a typical medium roast scoring around Agtron 50.

Coffee Species & Varieties

The three primary coffee species are Arabica, Robusta, and Liberica. Arabica, originating from Ethiopia, is considered the highest quality and is predominantly grown at high altitudes. It accounts for the majority of specialty coffee production due to its superior cup profile.

Coffee Processing Methods

Non-washed (natural/dry) process involves drying coffee cherries with the fruit still intact, while washed (wet) process removes the pulp before drying, resulting in cleaner flavors and fewer defects. Washed coffee typically has lower impurity and defect rates, contributing to a more refined cup.

Common Coffee Defects

Unripe beans (green beans) exhibit grassy and unpleasant flavors. Defects include moldy, black, sour, fermented, and insect-damaged beans. These flaws can severely degrade coffee flavor if not removed during sorting. Quality roasters handpick defects before roasting to preserve cup integrity.

Storage & Aging of Coffee Beans

Storage beans are held in controlled warehouses to reduce moisture or improve maturity, making them easier to roast and potentially enhancing body. However, prolonged storage often diminishes acidity and aroma, with both producers and consumers generally agreeing that freshness preserves more vibrant flavor characteristics.

Bean Age & Freshness

New crop beans are harvested and sold within the same year, old crop beans the following year, and aged beans over two years post-harvest. Aged beans have lower moisture content but may lack the vibrancy of freshly harvested coffee.

Caffeine Content Across Species

Arabica contains about 1% caffeine, Robusta roughly 2%, and instant coffee typically 3%–6%. This variance affects both stimulation levels and flavor profiles, with higher caffeine often correlating to more bitter or harsh cups.

Coffee Competitions & Quality Standards

The Cup of Excellence (COE) is an annual competition initiated in Brazil (1999) and now held in countries like Guatemala, Panama, and Nicaragua. It selects top-quality coffees through rigorous evaluation by national and international judges, then auctions them globally to highlight exceptional single origins.

Processing & Sorting Terminology

Defective beans encompass moldy, dead, black, unripe, and fermented beans. If not removed before or after roasting, these spoil the final cup flavor. Proper sorting is critical for quality control in both green and roasted stages.

Sieve Analysis & Bean Sizing

Sieves classify beans by size using 1/64-inch holes. An 18/64-inch sieve retains beans larger than 18/64 inch, with higher sieve numbers indicating larger beans. This sorting improves uniformity in roasting and extraction.

Specialty Coffee Definition

While lacking a universal definition, specialty coffee generally denotes beans with distinct, memorable flavors and high cup quality. This category includes historically recognized premium designations like 'Old Number Coffee' and 'Platinum Coffee.'

Shade-Grown Coffee & Farming Practices

Shade trees, such as bananas or mangoes, protect coffee plants from direct sunlight, reducing frost and pest risks. This traditional method also enhances biodiversity and microclimate stability on farms.

Frost Damage in Coffee Production

Frost, particularly severe in Brazil’s Paraná region (1975–1976), can decimate coffee crops. The 1975 event destroyed 915 million trees, slashing Brazil’s output from 25 million bags to 8.2 million and spiking global prices from $0.60 to $3.36 per pound—demonstrating climate vulnerability in coffee agriculture.

Double Roasting Techniques

Double roasting involves interrupting the roast, cooling the beans, then roasting again. This method aims to address uneven drying or smooth out bean texture but often results in muted flavors and a less complex cup profile.

Coffee Leaf Rust (Hemileia vastatrix)

This fungal disease affects coffee leaves in humid regions, forming yellow spots that hinder photosynthesis. Highly contagious, it devastated Arabica plantations in Ceylon (Sri Lanka) and Indonesia, leading to mass replanting with disease-resistant Robusta varieties.

Frequently Asked Questions

What does Agtron mean in coffee roasting?

Agtron is a numerical scale (100 to 25) used in the U.S. to measure roast degree, with 100 being lightest and 25 darkest. A typical medium roast scores around Agtron 50, determined using the Agtron M-Basic colorimeter.

What are the main coffee species?

The three primary coffee species are Arabica, Robusta, and Liberica. Arabica, originating from Ethiopia, is considered the highest quality and is mainly grown at high altitudes, while Robusta is more bitter and higher in caffeine.

What is the difference between washed and natural coffee processing?

Washed (wet) process removes the coffee cherry pulp before drying, resulting in cleaner, brighter flavors with fewer defects. Natural (dry) process dries the cherry with the fruit intact, often producing sweeter but more rustic cups with higher risk of defects.

What are common coffee bean defects?

Common defects include unripe (green), moldy, black, fermented, and insect-damaged beans. These can ruin flavor if not removed during sorting, which is why quality-focused roasters handpick defects before roasting.

Why is bean age important in coffee quality?

New crop beans are harvested within the same year, offering vibrant flavors. Old crop beans (next year) and aged beans (over two years) may lose acidity and aroma, with aged beans often having lower moisture but duller cup profiles.

What is the Cup of Excellence competition?

Cup of Excellence (COE), starting in Brazil (1999), is a prestigious coffee competition that selects top-quality single-origin beans through expert judging, then auctions them globally to highlight exceptional lots.

How does sieve size affect coffee beans?

Sieves classify beans by size using 1/64-inch holes. Higher sieve numbers (e.g., 18/64 inch) retain larger beans, improving roast uniformity and extraction consistency during brewing.

Recommended FrontStreet Beans for Beginners

Start your coffee journey with FrontStreet Coffee’s Ethiopia Humbera (Yirgacheffe), known for its bright floral notes and berry complexity in a classic washed profile. For a sweet and smooth introduction, try the Brazil Queen Manor with its creamy peanut and chocolate notes. Alternatively, the Lintong Mandheling offers a heavier body with spicy, earthy tones in a traditional Indonesian style. All are approachable yet representative of their origins. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.