Real-time Caffeine Monitoring at 2 ppm Accuracy

Dec. 1, 2011
While it may mystify those of us that need strong coffee to get through the workday, some people actually drink decaf, whether for health reasons, pregnancy cautions or personal preference.

USDA standards say decaf coffee is supposed to have its caffeine content reduced by no less than 97.5% of the source coffee. For both reasons, measurement is important. Moreover, coffee producers can benefit from automated caffeine measurement. Real-time caffeine monitoring can be used to conclude the decaffeination cycle as soon as the specified caffeine threshold is achieved, thus wasting no more caffeine solvent or production time than absolutely necessary.

The high-performance liquid chromatography currently used in some caffeine applications is quite costly to own and maintain while delivering slow response. But an online analysis solution can provide continuous, live caffeine measurement in an automated fashion. Here’s how, according to engineers at Applied Analytics, Inc. (AAI,

While certain selective solvents are extremely effective at removing caffeine from coffee beans, many of these chemicals have been classified as carcinogenic or toxic. Though less powerful, the supercritical CO2 extraction method is a harmless decaffeination process common in large-scale operations. Supercritical CO2 fluid is a hybrid gaseous/liquid resource maintained by exceeding the critical temperature (31 °C) and pressure (73 atm) of CO2; for the supercritical CO2 to act as an effective solvent for caffeine molecules, it actually has to be kept at more extreme conditions (around 94 degrees C and 225 atm). These conditions are expensive to maintain, and the 10-hour process cycle is time-consuming; the caffeine extract is sold off to pharmaceutical and soft drink companies, but this only partially alleviates process cost.

With real-time caffeine monitoring at ±1 ppm accuracy, a product like AAI’s OMA-300 Process Analyzer allows decaf coffee producers to automatically end an extraction cycle when the specified caffeine maximum is reached. Doing away with the preset 10-hour cycle, this method banishes both overprocessing (which wastes production resources) and underprocessing (which upsets customers). While highly suitable for monitoring the 0-1,000 ppm caffeine range established by international standards as “legally” decaf, the unit's UV-VIS spectrophotometer has a true detection limit of 2 ppm caffeine, thus theoretically capable of validating a cup of perfect decaf.

Renee Robbins Bassett, [email protected], is Managing Editor of Automation World.

This article was adapted from one produced by AAI. Read about the OMA-300 Process Analyzer at

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