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The roast color classification system: technology designed to advance the art & science of coffee roasting.

The Agtron/SCAA Roast Color Classification System is now available through the association's fulfillment center, according to Ted Lingle, executive director of the Specialty Coffee Association of America. This much anticipated tool for the coffee trade was unveiled at SCAA's 7th annual Conference and Exhibition at Long Beach, California.

The project was developed over a two-year period by one of the world's leading experts in food science technology, Carl Staub of Agtron, Inc., in conjunction with SCAA's Technical Standards Committee.

According to Lingle, "The objective was to provide the international coffee trade with a standardized system for classifying various degrees of roast. This method of roast classification provides an objective language to communicate the degree of roast for any given sample."

Speaking before a crowded audience at a seminar entitled; Roast Color Classification System Using the Agtron/SCAA Color Disks, Staub stated, "One of the many quality control challenges facing the specialty coffee roaster is consistency. Both classification and quality of roast become the priorities of day-to-day production. Certainly the most accurate quality control programs employ sophisticated equipment and chemical analysis to determine quality index and degree or classification of roast, but such elaborate measures are beyond the financial and technical resources of most roasters." He continued, "The objective of the roast classification project was to produce a number of color disks that could be used to classify various degrees of roast. The basis of the classification is the progression of sugar chemistry under controlled roasting conditions."

Staub and coffee experts created the Agtron/SCAA Roast Color Classification System to provide trade professionals with an affordable and (accurate as possible) tool for visual comparison. Staub revealed, "With any type of visual comparator, many factors affecting color perception must be accommodated. Knowing the weaknesses of this type of system, we can only state that while such a system can move us closer to a common language and standard, it cannot be used as an absolute measure, but more as an indicator or approximator. While a color disk set for classification is a useful tool, it should be used in conjunction with cupping to enhance the system's accuracy. He emphasized, "By combining the color disk system with cupping, it is possible to obtain a classification that will be within five points of the absolute value."

Creating the Instrument

Staub explained, "Cupping is the ultimate assessment of roast quality, and there is no substitute for a keen or trained palate. But when it comes to classifying the degree of roast, the specialty coffee industry has [heretofore had] no established standards or references. To complicate matters, it seems that no two individuals can agree on the language or nomenclature or roast classification."

In designing the new system, SCAA's Technical Standards Committee (of which Staub is a member) recognized that the terminology used by the trade to describe roast color is highly subjective. The team agreed to devise a new vocabulary in favor of using traditional nomenclature to describe the degrees of roast. By referring to each of the roasts by number, the committee developed a new language. Thus, a precise, standardized vehicle for describing roast color was established.

According to Staub, "A scientific roasting scheme was used to prepare samples [of roasted, ground coffee], and a linear chemical progression was used to establish the absolute development or process index, based on sugar carmelization. A consensus of opinion [among experienced roasters] was used to establish the anchor point for extremes of classification (i.e., the darkest roast color commonly offered by the trade versus the lightest roast color accepted by the trade)." He continues, "Participating SCAA member roasters submitted three samples each from three separate roasts that each member produced as their darkest roast." (SCAA received more than 250 coffee samples.)

"By eliminating the highest and lowest 10% of the samples," noted Staub, "the average darkest roast value was 30 on the Agtron scale, which established the lower limits." He explained, "In a separate blind cupping conducted by SCAA, samples were roasted at the chemistry indexes of 100, 95, 90, 85, and 80. These samples were labeled out of sequence with the letters A, B, C, D, E, and E Seven of the 10 cuppers selected the 90 classification as the lightest roast, establishing the scale's upper limit. These classifications selected by sensory consensus established the dynamic range of the scale."

The System "Kit"

SCAA's Roast Color Classification System is comprised of a lightweight black vinyl kit (10 in. by 12 in. by 1-3/4 in.) containing eight color disks, numbered in 10% increments ranging from "Very Light" (tile #95) to "Very Dark" (tile #25). The kit also includes four black background sheets, two standard small Pyrex petri dishes for sample preparation, and an easy-to-use, 10-page manual. Written by Carl Staub, the accompanying handbook gives step-by-step instructions for using the Roast Color Classification System.

According to the author, "It is very important to read the manual first. The book is concise and clearly written. The user must learn to prepare consistent samples - consistency is very important. The rest is self explanatory."

When asked which members of the coffee trade should use the new Roast Color Classification System, Staub replied, "Anybody who roasts or cups coffee." In addition to roasters and roaster retailers, he encourages importers, exporters, dealers, retailers, and chefs to use the system for quality control.

Staub who is passionate about coffee, believes that the Agtron/SCAA Roast Color Classification System will enable specialty roasters to be more creative. "I am hoping that people will discover a whole range of roasts," he commented. "This system is based on good chemistry and science, and solves a problem that's been around for hundreds of years. I hope that it will bring tremendous respect to SCAA and move the coffee industry into the future.

The Evolution

SCAA's Technical Standards Committee was established in the autumn of 1992. During the first "Tech Standards" meeting, Gerald Baldwin (the chairman at that time) and committee members formalized their mission. The committee established these specific objectives:

To establish methods and measurement standards for all coffee processes from seed to cup; to test new methods for validity; as well as to collect and publish up-to-date information reflecting either or both of the traditional and newly established standards of quality.

To that end, committee members embarked on their first project. Mary Townsend and other specialty coffee trade professionals created SCAA's Green Coffee Contracts and Arbitration Handbook. After completing these initial assignments, the committee began yet another ambitious and important project, developing the roast color classification system.

During the next two and a half years, Carl Staub and his colleagues at Agtron along with Ted Lingle and volunteer committee members spent many hours creating an inexpensive, simple yet effective system with a new vocabulary for roast quality control.

Now that work on the Agtron/SCAA Roast Color Classification System is complete, SCAA's Technical Standards Committee is focusing on yet another resource for the specialty coffee trade, SCAA's Coffee Brewing Handbook.

Looking toward the future and new projects, Ted Lingle comments, "The standards for green coffee classification, roast color classification, and brewing evaluation will assist SCAA members in making a quantum leap into 21st Century quality control.


Carl Staub is president of Agtron, Inc. of Sparks, Nevada. After earning his undergraduate degree in physics and electrical engineering, he received a masters degree in electrical engineering. Agtron designs and manufactures super abridges spectrophotometers, primarily for the food and beverage industries. The company sells its products in 26 countries.

Agtron has created units to analyze specific characteristics of many food products including wines, cereals, orange juice, chocolate, vegetables, frozen foods, and grains. Moreover, the company has developed and produced USDA color guidelines for more than 30 different food products.
COPYRIGHT 1995 Lockwood Trade Journal Co., Inc.
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Copyright 1995 Gale, Cengage Learning. All rights reserved.

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Author:Pugash, Melissa
Publication:Tea & Coffee Trade Journal
Date:Jul 1, 1995
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