Researchers from the Quadram Institute used a new technique they have developed to distinguish between superior Arabica coffee and cheaper, lower quality Robusta.
Arabica coffee trades at up to twice the price of Robusta due to its ‘superior’ taste, and because Robusta plants are higher yielding and easier to grow.
This makes adulteration of Arabica with cheaper Robusta coffee an attractive possibility to fraudsters.
Dr Kate Kemsley, research leader at the Quadram Institute, said: “It was immediately obvious using our test that there were several suspicious samples, producing results that were consistent with the presence of substantial amounts of Robusta – far more than would be expected through unavoidable contamination.”
Distinguishing between the two types of coffee is difficult, especially when they have been roasted and ground, according to the Quadram Institute.
Identification relies on chemical analysis of the many different compounds in the coffee, as the major components are broadly similar.
The current standard analytical technique is expensive and takes three days, making it impractical for large surveillance studies to detect fraud.
The equipment used by Quadram Institute uses radio waves and strong magnets to get detailed information about the molecular composition of a sample, taking three days to 30 minutes. The instrumentation is robust enough for industrial use.
The method is sensitive enough to detect just 1% Robusta in an Arabica/Robusta blend.
A total of 60 different samples originating from at least 11 different coffee-growing countries and regions were purchased by Quadram Institute staff and collaborators from across the world.
The Institute notes that better surveillance, which the new technique could help deliver, will protect consumers as well as ensuring that the farmers involved receive a fair price for their produce.
The research was funded by the Biotechnology and Biological Sciences Research Council and published in the journal Food Chemistry.