Traditionally, the only way of checking the purity of Arabica coffee involves testing samples for the presence of a chemical known as 16-O-methylcafestol (16-OMC) – it has long been thought that the compound is present in Robusta beans, but not in Arabica. Unfortunately, samples need to be sent off to a lab for analysis, and processing of those samples takes approximately three days.
Researchers from Britain’s Quadram Institute have discovered that a Pulsar benchtop NMR (nuclear magnetic resonance) spectrometer made by Oxford Instruments can do the same thing on-site in just 30 minutes. The device uses radio waves and magnetic fields to obtain information about the molecular composition of a sample, and can reportedly be easily operated by non-specialists. It’s previously been utilized to detect horse meat in ground beef.
In lab tests, it was used to analyze 60 samples of supposedly 100-percent Arabica coffees gathered from 11 different coffee-growing countries and regions around the world. While 90 percent of those samples were deemed to be pure, the rest had high enough 16-OMC levels to indicate fraud.
The spectrometer can detect Robusta concentrations as low as 1 percent in blended coffees. In fact, it turned out to be sensitive enough to reveal that even Arabica beans do contain small amounts of 16-OMC. Therefore, the testing procedure had to be adapted to allow for a threshold amount of the chemical, which will be detected regardless of whether or not Robusta is present.
Source: Food Chemistry