Green Coffee

Green coffee refers to unroasted coffee beans in their raw state, containing hundreds of chemical compounds including carbohydrates, proteins, lipids, acids, and alkaloids like caffeine. The composition of green coffee significantly influences the flavor of the roasted product. To understand how these compounds transform during the roasting process, explore our comprehensive guide to Roasting Chemistry.

Green coffee is far more stable than roasted coffee, as the intact cellular structure and low moisture content slow oxidation. However, once roasted, the bean's cellular structure breaks down, exposing lipids and volatile compounds to oxygen. To understand how roasted coffee degrades over time, see our guide to Oxidation and Staling.

Green Coffee Chemical Composition

The chemical makeup of green coffee is the foundation upon which all roasted coffee flavor is built. Green coffee beans contain over 200 identified chemical compounds, and this composition varies by Arabica species versus Robusta, by origin country, by altitude, and by processing method. Understanding these components is essential for roasters who seek to predict how a given lot will behave under heat.

Carbohydrates and Sugars

Carbohydrates constitute the largest fraction of green coffee, accounting for approximately 50 to 60 percent of dry weight. The primary carbohydrate components include sucrose (6 to 9 percent in Arabica, 3 to 5 percent in Robusta), reducing sugars like glucose and fructose (0.1 to 1 percent), and polysaccharides such as arabinogalactans, mannans, and cellulose. Sucrose is particularly important because it serves as a primary fuel for the Maillard reaction and caramelization during roasting, directly contributing to the brown color and sweet, caramel-like flavors of roasted coffee. Higher sucrose content in green coffee generally correlates with higher cup quality scores.

Lipids and Coffee Oil

Lipids, primarily triglycerides and diterpenes like cafestol and kahweol, make up 10 to 15 percent of green coffee by weight. These coffee lipids contribute to body, mouthfeel, and crema formation in espresso. Arabica typically contains more lipids than Robusta. The lipid fraction also includes free fatty acids, sterols, and tocopherols, which play roles in flavor stability and nutritional properties of the brewed cup.

Chlorogenic Acids

Chlorogenic acids (CGAs) are a group of phenolic compounds that account for 5 to 8 percent of green coffee dry weight in Arabica and 7 to 10 percent in Robusta. CGAs contribute to the acidity, bitterness, and astringency of coffee. During roasting, CGAs degrade into quinic and caffeic acids, which influence the flavor profile. CGAs are also valued for their antioxidant properties and potential health benefits, which is why green coffee extract is sometimes used in dietary supplements.

Caffeine and Alkaloids

Caffeine content in green coffee ranges from approximately 0.8 to 1.4 percent in Arabica and 1.7 to 4 percent in Robusta. Caffeine is remarkably stable during roasting, with only minimal degradation at typical roast temperatures. Other alkaloids present include trigonelline, which degrades during roasting into niacin (vitamin B3) and various volatile compounds that contribute to aroma.

Proteins and Amino Acids

Green coffee contains 10 to 13 percent proteins and free amino acids. These are critical reactants in the Maillard reaction, combining with reducing sugars during roasting to produce hundreds of flavor compounds including furans, pyrazines, and melanoidins. The amino acid profile of green coffee varies by variety and growing conditions, contributing to the terroir-driven flavor differences between origins.

Minerals and Ash

Minerals account for 3 to 5 percent of green coffee and include potassium (the most abundant), magnesium, calcium, sodium, iron, and trace elements. Potassium plays a particularly important role because it affects extraction dynamics during brewing. The mineral content of green coffee is influenced by soil composition and fertilization practices at the farm level.

From Cherry to Green Coffee: Processing and Preparation

Green coffee does not emerge from the coffee plant ready for trade. It undergoes a series of processing steps that transform the freshly harvested coffee cherry into the stable, dry green bean. The processing method chosen at the farm level profoundly influences the flavor of the final roasted product.

The three primary processing methods are the washed process, where the cherry skin and mucilage are removed before drying; the natural process, where the entire cherry is dried intact; and the honey or pulped natural process, where the skin is removed but some mucilage remains during drying. Each method imparts different flavor characteristics and affects the chemical composition of the green coffee.

After processing, green coffee undergoes milling, which removes the parchment layer and any remaining fruit residue. The beans are then sorted by density, size, and defect count before being bagged for export. The final step in the supply chain is export preparation, where green coffee is packaged for international shipment.

Green Coffee Grading and Quality Assessment

The Specialty Coffee Association (SCA) has established a comprehensive green coffee grading system that categorizes beans based on defect count, screen size, moisture content, and sensory evaluation. This system is the industry standard for determining whether a lot qualifies as specialty grade, which commands a premium price.

Defect Classification

Green coffee defects fall into two categories. Primary defects are severe quality issues that each carry significant weight in grading calculations. These include full black beans, full sour beans, quakers (unripe or underdeveloped beans), stones, sticks, and foreign matter. Secondary defects are less severe and include partial black or sour beans, insect-damaged beans, broken beans, shells, and slight discoloration. A specialty grade lot must have no more than 5 full defects per 300 gram sample.

Screen Size and Density

Screen size, measured in 1/64 inch increments, indicates bean size and uniformity. Larger and more uniform beans generally roast more evenly. Common Arabica screen sizes range from 14 to 18, with 18 being the largest. Density is assessed visually and by touch, with denser beans (often from higher elevations) being preferred for their more complex flavor potential.

Moisture and Water Activity

Moisture content is measured with specialized meters and should fall between 10 and 12 percent. Water activity, a more precise measure of available moisture, should be between 0.45 and 0.55. These metrics are critical because improper moisture levels can lead to mold growth, accelerated staling, or bean fracturing during roasting.

Cupping and Sensory Evaluation

Beyond physical grading, green coffee is evaluated through cupping, a standardized tasting protocol. A licensed Q-grader roasts a small sample, brews it according to SCA protocols, and scores it on a 100 point scale evaluating fragrance, aroma, flavor, aftertaste, acidity, body, balance, uniformity, cleanliness, sweetness, and overall impression. Scores of 80 to 84.99 qualify as specialty, 85 to 89.99 as excellent, and 90 and above as outstanding.

Green Coffee vs Roasted Coffee: Key Differences

Characteristic	Green Coffee	Roasted Coffee
Color	Green to greenish-blue	Brown to dark brown/black
Moisture content	10 to 12 percent	1 to 5 percent
Shelf life	12 to 24 months	2 to 6 weeks optimal
Density	High, dense structure	Lower, porous structure
Aroma	Grassy, herbaceous, minimal	Complex, hundreds of aromatic compounds
Caffeine content	0.8 to 4 percent by species	Minimal change from green
Sucrose content	6 to 9 percent (Arabica)	Near zero (consumed by roasting)
Chlorogenic acids	5 to 10 percent	1 to 3 percent (degraded during roast)
Cellular structure	Intact, stable	Fractured, porous, fragile
Flavor when brewed	Astringent, sour, grassy	Complex, balanced, aromatic

Green Coffee Storage Best Practices

Proper storage of green coffee is essential for preserving quality from the time it leaves the farm until it is roasted. The key environmental factors to control are moisture, temperature, oxygen exposure, and pest contamination.

Temperature should be maintained between 60 and 70 degrees Fahrenheit. Fluctuating temperatures cause condensation inside storage bags, which can lead to localized mold growth. Humidity should be kept between 50 and 60 percent to prevent both moisture gain and loss. Green coffee is hygroscopic, meaning it absorbs or releases moisture depending on ambient humidity, so stable conditions are paramount.

Traditional storage in jute burlap bags allows breathability but offers limited protection against moisture and oxygen. Modern specialty coffee storage increasingly uses hermetic barrier bags like GrainPro, which create a sealed environment that protects against moisture, oxygen, and pests while preserving the green coffee's original flavor profile for extended periods.

Pest control is another critical consideration. The coffee borer beetle can infest green coffee during storage, boring into beans and causing primary defects. Integrated pest management strategies, including temperature control, hermetic storage, and regular inspection, are essential for preventing infestations.

The Global Green Coffee Trade

Green coffee is one of the most widely traded agricultural commodities in the world, with global production exceeding 10 billion kilograms annually. The commodity market price, known as the C-price, is set on the Intercontinental Exchange (ICE) and fluctuates based on supply and demand fundamentals, weather events in producing countries, and macroeconomic factors.

The green coffee supply chain typically involves producers (farmers and cooperatives), processors (washing stations or dry mills), exporters, importers, brokers, and roasters. In the specialty coffee segment, shorter supply chains are common, with roasters often purchasing directly from producers through direct trade relationships that emphasize quality, transparency, and fair compensation.

Green coffee is shipped internationally in containers holding approximately 250 to 300 bags of 60 kilograms each, or about 18,000 kilograms per container. The transit time from producing countries in Latin America, Africa, or Asia to consuming markets in North America, Europe, or East Asia can take several weeks, during which temperature and humidity fluctuations inside shipping containers can affect bean quality.

Expert Tips for Evaluating Green Coffee

• Assess uniformity: Beans of consistent size and color roast more evenly. Look for uniform green to bluish-green coloration without significant variation.
• Check moisture immediately: Use a calibrated moisture meter upon receipt. Beans outside the 10 to 12 percent range should be flagged for potential quality issues.
• Smell the green coffee: Fresh, high-quality green coffee has a clean, grassy, or hay-like aroma. Off-notes like fermentation, mold, or mustiness indicate quality problems.
• Count defects systematically: Spread a 300 gram sample and sort by defect type. Even a few primary defects can signal broader quality issues in the lot.
• Roast a sample: A sample roast and cupping evaluation remains the definitive method for assessing green coffee quality. Physical grading alone cannot predict cup character.
• Document lot information: Maintain records of origin, variety, processing method, harvest year, and arrival moisture. This traceability is increasingly important for quality management and customer communication.

Glossary of Key Green Coffee Terms

Defect

Any imperfection in green coffee that negatively affects cup quality, classified as primary (severe) or secondary (moderate). See our entry on Defects.

GrainPro bag

A hermetic storage bag that creates a sealed, low-oxygen environment to preserve green coffee quality during transport and storage.

Water activity (Aw)

A measure of available moisture for microbial growth, more precise than total moisture content. Ideal range for green coffee is 0.45 to 0.55.

Screen size

The physical size of green coffee beans, measured in 1/64 inch increments. Larger, more uniform beans generally command higher prices.

C-price

The commodity market price for Arabica green coffee, set on the Intercontinental Exchange. Specialty coffees are typically priced at a premium above the C-price.

Cup of Excellence

A prestigious green coffee competition and auction program that identifies and rewards the highest quality lots from participating producing countries.

Resting period

The time between harvest and shipping during which green coffee stabilizes. Also refers to the period between roasting and brewing, though the concept applies differently in each context.

The cocoa and dark-chocolate notes that define many darker roasts are dissected in our chocolate coffee flavor profile, which traces those flavors to Maillard browning products and pyrazines formed late in the roast.