New test detects adulterated coffee grounds

A new test can detect ground coffee adulterated with cheap filler ingredients with 95 per cent accuracy, according to Brazilian researchers.

While not generally harmful to health, the practice of lacing coffee with substances like corn, barley, wheat, soybeans, rice, beans, acai seed, brown sugar or starch syrup represents a form of economic fraud and is on the increase on the back of reduced supplies of coffee beans in the marketplace, say the team from the State University of Londrina in Brazil.

"With a lower supply of coffee in the market, prices rise, and that favours fraud," according to lead researcher Suzana Lucy Nixdorf, who presented the research at this week's National Meeting & Exposition of the American Chemical Society (ACS) in San Francisco.

A test to detect counterfeit coffees is becoming more important in light of growing shortages in regions, such as Brazil, where droughts and plant diseases have dramatically cut back coffee supplies.

Brazil typically produces 55 million bags of coffee each year. But according to some reports, the projected amount for 2014 will likely only reach 45 million bags after this January's extensive drought. That equates to about 42 billion fewer cups of coffee for this year.

Adulterants added to the ground coffee can be hard to spot, especially after roasting and grinding, because of the "dark colour and oily texture of coffee," said Nixdorf, who believes that these are generally added deliberately and not accidentally, as some coffee producers have claimed.

Currently, tests to detect these unwanted additives require scientists to check the coffee, and those tests are subjective, not quantitative, according to Nixdorf.  With these tests, the scientists look at the coffee under a microscope or identify various additives by simply tasting the coffee. In contrast, the new test uses liquid chromatography and statistical tools. This gives the team a much closer look at the ingredients in an unbiased way.

Because much of the coffee is composed of carbohydrates, researchers could develop a characteristic fingerprint when using chromatography that separates out the real coffee compounds, according to Nixdorf. The added, unwanted grain fillers generate different levels of sugars than the natural ingredients, so they are easy to identify.