STiR coffee and tea magazine

Volume 4, Number 4

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STiR tea & coffee industry international 33 Agtron managing partner Carl Staub The meaning of scores Today, because of modern spectrophotometry (the science of measuring how much a substance absorbs light by measuring the intensity of a beam as it passes through a sample) some of the most precise instruments use a light source outside the visible spectrum to illuminate samples. Some experts in spectrophotometry get annoyed when coffee consultants refer to one of the commonly used scales as referring to color. Carl Staub, managing partner of Agtron Inc., explained that near-infrared spectrophotometry (NIR) involves measur- ing selected wavelengths of energy reflected from the surface of a sample substance. This is not energy that can be seen by the eye, and therefor to describe it as a color measurement is incorrect. Staub's point is well-taken. Just because an instrument can report findings in an Agtron number does not mean that it is using NIR to take those measurements. Color meters shine light and measure the reflectance based on the specific instru- ment's capabilities. Those measurements then go through a software-automated, post-measurement interpretation to be able to provide a score meant to be equiva- lent to an Agtron score. The latest light-measuring tools The coffee industry would be nothing if not full of ongoing debate. There is much in general food science research that would seem to validate the assertion that NIR is a better tool for analyzing roast degree and therefore predicting flavor than instruments that use visible light. Not everyone agrees. In a white paper, "Color Measurement of Roasted Coffee us- ing HunterLab Spectrophotometer" published in 2014 by a team at Hunter Associates Lab, Inc., the authors noted "IR spectroscopy has the potential to provide information on weight loss and moisture content, chemical composition, and other related proper- ties of coffee. However, the combination of these broad range of capabilities are rarely found in a single NIR instrument suitable for industrial quality and process control..." In other words, most such tools are far too expensive for many businesses and typically found in academic or research and development settings. Paul Barnes, Americas sales manager for HunterLab, suggested small but grow- ing coffee roasters consider adding the ColorFlex EZ Coffee to their quality control program. The device has a small footprint with a width of 5.1 inches, a height of 6.3 inches, and a depth of 14.2 inches weighing in under 10 pounds. The pulsed Xenon lamp sends one flash per measurement up through a disposable sample cup and takes reading in the visible light spectrum (400nm-700nm). For large volume plants, Barnes recommended the D25NC with coffee scales. The D25NC is a larger and heavier tool with a width of 14 inches, a height of 14 inches, and a depth of 19 inches weighing in at about 30 pounds. With it, the light source is a full spectrum, solid state LED system with an expected life of about five years. Like the ColorFlex EZ Coffee, it takes measurements in the visual spectral range, however it uses bursts of 25 flashes in one measurement cycle to give one averaged reading. Agtron's latest instruments are the M-BASIC II and E20-CP/II. As the name sug- gests, the M-BASIC II is the less sophisticated. However, both models use NIR illu- mination. The M-Basic via a solid-state lamp expected to last about 9 years; the lamp in the E20-CP/II, also solid-state, is rated to last about two years longer. Both models feature good analyzer to analyzer agreement. This feature is one sought after by large companies with multiple roasting plants who need to meet similar flavor profiles in coffees roasted in more than one facility worldwide. What makes the E20-CP/II more sophisticated is that it uses fully automated digital calibration and enables the opera- tor to use both the commercial and gourmet Agtron scale through a keypad interface. Two other tools worth noting are the Colorette 3b from Probat and the 580-PC from Photovolt. Both are smaller in size than the ColorFlex EZ and both present measurements to the operator using the SCAA Roast Coffee Classification numbers. Modern instruments like the 580-PC track a bean during its journey from first crack... all the way through brown, and very dark (nearly black) roasts, said Hildreth. "With classification of roasts so easy, roasters find time to focus on a broader range of roast recipes," she said. ColorFlex EZ Coffee from HunterLab HunterLab D25NC with scale

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