Coffee grading: definition, criteria, and impact

Coffee grading: definition and summary

Coffee grading is a way of separating and categorizing green coffee beans for packaging and sales to wholesalers or roasters. It is a way for all involved in the transaction to have a common frame of reference when talking about the condition and setting value for coffee beans.

Coffee grading system

Coffee grading systems were developed to help ensure consistency and the highest quality across the coffee supply chain, giving growers, buyers and consumers a common frame of reference when doing business. Having a coffee grading system allows use of a set of standards and procedures to determine and evaluate the quality of green coffee beans.

There are several factors that go into coffee bean grading criteria, including bean size, bean defects, moisture content and cup (or taste) quality. Because coffee is grown in different regions around the globe, and across several national boundaries, different countries have created and use their own coffee grading systems, like the Kenyan coffee grading system, or Brazilian coffee grading system, among other countries. The Specialty Coffee Association (SCA) created the SCA Green Arabica Classification System, which is most widely used across the specialty coffee industry to determine the quality of beans.

Coffee bean grades and classification

Green coffee beans are classified and separated into different grades based on their quality and physical characteristics, with the highest-grade beans considered specialty coffee, with minimal defects and a high cup (or taste) quality. In general, the fewer the defects, the higher the overall quality.

Premium coffee beans are a step down from specialty beans and are still considered a high quality. Premium beans have fewer defects, contributing to their better quality and thus producing a better flavor profile. Beans considered commercial grade are of lower quality, with more defects and a less desirable flavor profile. Low-grade coffee beans are used by some coffee manufacturers to create coffee blends and instant coffee products. These are beans that are not suitable for either specialty or premium coffee.

Screen sizing of coffee

Coffee beans come in many shapes and sizes. Coffee size is determined by measuring it against a rounded inch, with 20/64 the largest size and 8/64 the smallest. In this range is where you find all the acceptable screen sizes in coffee. Before being bagged by the seller, the coffee is poured through large sieves with holes that separate the coffee by size. The larger beans stay at the top while the smaller beans fall through the lower screens. After separating them by size, the beans are bagged per screen.

Factors affecting coffee quality

The taste and quality of coffee can be affected by a range of factors, including things that affect the growing of the coffee plant, like growing altitude, crop soil, climate and weather, and how the coffee beans are processed. Coffee trees produce coffee fruit, or cherries, inside of which the coffee bean grows. Once extracted from the cherries, bean size and moisture content level become more critical for coffee grading and determining the quality of coffee beans.

Coffee flavor profiles can be affected by the level of roasting the beans undergo. Lighter roasting creates a more acidic taste, with darker roasts creating a bolder taste. Beans that are roasted need to be similar in size, so the beans roast evenly. Different sized beans roast at different lengths, so smaller beans with roast faster than larger ones, leading to uneven roasting. That is why beans are separated by screen size, allowing the smaller beans to pass through different sized holes and be separated, allowing for a more consistent roasting. Quality control measures are crucial for achieving a roast that brings the best flavor from the coffee beans.

Cleaning and processing

Before roasting, coffee beans need to be prepared. Proper cleaning is required. Washing the beans helps remove any impurities and some defects. Processing methods like washing or sun drying will have an effect on the quality of the beans.

Cupping and roasting

Roasting and cup quality are important processes evaluating a batch of coffee beans. As we mentioned, different roasting levels will significantly impact the flavor profile of coffee. Darker roasting produces a bolder flavor and can also be used to cover low quality beans by masking some of the undesirable flavors. The best way to evaluate the quality of the beans is cupping them. Brewing and tasting the coffee for cup quality is the best way to assess its flavor profile, acidity, and body.

Cup faults, problems with taste or aroma of the coffee, cannot be detected until the beans are roasted and brewed. By applying quality protocols, like the SCA cupping protocol, a coffee is assessed on balance, uniformity, cleanliness, sweetness, body, acidity, fragrance/aroma, and flavor. A cupping protocol that is agreed upon by the buyer and seller can help streamline any conversations about the quality of the coffee.

Recognizing defects in coffee beans

Defective coffee beans, or imperfections found in coffee beans are called defects. Finding and evaluating these defects is important to determining the quality and value of a harvest of beans. There are two classifications of defects found, primary and secondary defects. Defective beans can be rejected or downgraded, depending on the severity of the defect.

The defect count, or the number of defects allowed in each batch, is set depending on the defect. The fewer defects found, the higher the coffee grading will be. One of the primary classification systems for categorizing defects is the SCA Green Arabica Classification System, or GACCS for short. GACCS distinguishes primary and secondary defects.

Primary defects will have a significant impact on quality, like black beans, full sour beans, and larger foreign objects. A single Category 1 defect can disqualify a coffee from being considered specialty coffee grade. Secondary defects are less severe, but you still do not want them in your coffee, like broken beans, insect-damaged beans (minor), unripe beans, and shells. A certain number of Category 2 defects can be equivalent to one Category 1 defect in grading.

Best methods call for visual inspection of the beans will uncover many of the defects, like bug damage and black beans (caused by overfermentation, or other bad things). Cupping is also an essential part of the process, as taste is another way to detect defects in the coffee beans.

The importance of elevation

The elevation where a coffee bean crop is grown plays a significant role in the quality of the coffee beans. When grown at higher altitudes, coffee beans mature at a slower rate, meaning they develop more complex flavor profiles as they grow. This is why elevation of growth should be one of the factors to consider when evaluating the quality of beans.

What is the U.S. Coffee C Futures Market?

Similar to the stock market, the C Market is the global commodity exchange where both the physical trading of green coffee and the trading of coffee futures contracts are traded. For coffee to be exchange traded, it must first meet certain criteria. The Coffee C Futures contract is traded on the intercontinental Exchange (ICE) and is the global benchmark for Arabica coffee prices. It is the expected price of coffee for delivery at a future date, allowing market participants to hedge against price fluctuations.

Global prices and Coffee C Futures

As globally traded on the commodities markets, the price of green Arabica coffee beans is set on the US Coffee C Futures market, which influences how much coffee-producing countries can sell their beans for. That is why the base price for green coffee goes up, the price of specialty coffee beans also goes up, because it is tied to the futures market fluctuations.

StoneX Specialty Coffee: trading, options, futures and sourcing solutions

At StoneX, we leverage our extensive global network and market expertise to assist producers, exporters, importers, traders, and end users in enhancing hedging strategies, optimizing pricing, and physically trade across the coffee market. Contact our coffee team for details. For the latest coffee news and thought leadership articles, please visit Coffee News at StoneX Specialty Coffee. You can also subscribe to in-depth insight and analysis on the coffee market with our detailed market reports.

FAQs

How does coffee grading influence price? 

Coffee grading systems were designed to apply value to beans of varying quality based on factors including physical defect count, moisture content, insect damage or bean rot. Beans are separated by size before grading, with a different value applied to each of the size classes. Large beans cost more, small beans cost less.

Once separated by size, beans are graded as separate classes, but each class is judged by the same standards in terms of defects, moisture, and overall bean quality, with beans of higher quality and fewer defects commanding a higher price.

What is the highest coffee grade? 

The highest quality grade in coffee beans depends on what coffee grading system is used to grade the coffee. Several countries, like Kenya and Brazil as two examples, have their own systems for grading coffee beans. While each system might classify its highest quality coffee in a different way, one calling it Grade A, another calling the same grade, AA, but no matter what grade it is given in each country, the standards for the grades are fairly consistent.

How do defects impact coffee quality and market value? 

SCA has set standards, and to be considered specialty grade coffee, green beans must have zero Category 1 defects and no more than five Category 2 defects in a 350g sample of green beans. Coffees with higher defect counts are given lower grades, which are priced considerably lower prices on the open market.

What grading systems are used in coffee-producing countries? 

Many people are unaware that coffee grading is not uniform across all the coffee-producing countries of the world. Each growing country assesses the beans based on specific criteria. The Specialty Coffee Association grading scale is the standardized method used to evaluate the quality of green coffee beans.

Beans are graded on a 100-point grading scale, designating 80 or above as a 'specialty coffee.' Professional coffee evaluators, called Q graders, are trained to assess coffee attributes, like acidity, body, flavor, aftertaste, balance, and overall cup cleanliness. This grading scale plays an important role in determining quality and influencing pricing across the entire specialty coffee market.

Ethiopia uses a grading system based on the number of defective beans, with grade from G1 to G5.

Kenya used a unique grading system based on bean size, with Grade E being the rarest.

Brazil follows its own grading system, a combination of particle size and defect found.

Colombia bases its grading by bean size using various screen diameter holes.

Ethiopia's grading system is based on growing regions and coffee taste profiles.

Can investors trade only high-grade coffee? 

No, investors can trade coffee based on the coffee's grade. Premium or high-grade coffee beans, as their name indicates, sell on the open market for a premium price. Mid- to low-grade green coffee beans are considered commodity grade and trade in millions of tons on a daily basis. Many large coffee producers purchase lower quality coffee beans for use in coffee blends and to create instant coffee.