Green Coffee Bean Physical Analysis
- Color analysis
- Degree of water activity
- Bean size
- Density
- Grading (defect count)
- Caffeine content
The value of green coffee is in its flavor and how it can be used. Some green coffees are quite valuable and have a long-standing reputation of high quality (Kenyan, Kona, Guatemalan Antigua, Jamaican Blue Mountain), not always deserved. Those that can be sold as a single origin command the highest prices. Next in line are lesser-known origins, some of which are every bit as good as the “stars,” but do not have a reputation in the marketplace. The “blenders” are coffees that may be all right on their own, but are usually blended with other components.
Standards/Definitions
In creating standards for a green coffee, the three primary issues are:
- Country (or region) of origin
- Physical characteristics
- Sensory standards (taste)
Green Coffee Country of Origin
This will determine the flavor profile of the product. This flavor is affected by soil composition, the climate in which the coffee was grown, and how the coffee is cultivated. The methods for processing and grading between origin countries vary significantly. The flavor of the coffee also changes seasonally, resulting in “past crop” flavors just before the new harvest and “grassy“ or “immature” flavors during or shortly after the harvest. This can be the most challenging area in creating a consistent product.
Coffee Analysts regularly visits growing countries to evaluate the coffees and methods of productions being used. Years of experience of working with individual coffees and how they combine in blends can assist in developing new products or continual monitoring of the consistency of existing products.
Physical Characteristics
The measured physical standards for determination of green coffee quality include:
- Bean Size; expressed as a percentage of screen size
- Moisture Content; expressed as a percentage
- Density; expressed as weight per volumetric measure
- Defect count; where a 300-gram sample is sorted for defects (black, sour, immature beans, etc.)
Performance of these tests allows one to evaluate the quality and consistency of the lot on several levels. The bean size and defect count determines the grade of coffee in most systems of grading. The bean size, moisture content, and density will give the roaster clues as to how much heat should be applied over what time interval to achieve the desired roast.
Sensorial Evaluation
This is subjective and therefore more difficult to measure. The traditional process is to establish a panel of individuals who have experience and knowledge in various types of coffee, along with familiarity with the specific blend and the individual components. Those appointed to this task should have a specific flavor profile in mind that can be shared with other testers, roasters, importers, brokers, and country of origin exporters.
Important Considerations
Considerable opportunity for quality control testing exists at the green coffee level due to the variability of the components. The potential flavor of the sample is determined by the species and variety of tree, the soil in which it is grown, climactic conditions, altitude, and cultivation practices. During processing (natural or wet), separation of the fruit from the seed, this flavor can be maintained or lost to varying degrees. Off-flavors, including ferment, can be introduced during processing as well. All coffee must be sorted after processing to eliminate the possibility of off-flavors caused by defective beans. Finally, the length of storage time and storage conditions can affect the flavor.
For more information on Coffee Analysts’ services, call TOLL FREE 1.800.375.3398, or send an email to info@coffeeanalysts.com.