Rapid NMR test detects quality and authenticity of olive oil

Researchers at the University of Bayreuth in Germany say they have developed a rapid test that can detect food fraud involving olive oil within an hour.

The test – based on nuclear magnetic resonance (NMR) spectroscopy – has been developed by the university with the help of the University of Athens, analytical specialist ALNuMed and live oil companies.

It has been refined over several years from analysis of more than 1,000 different samples of extra virgin olive oil, a perennial target for food frausters.

Counterfeiting and fraud is a big problem for the $16bn-a-year olive oil industry, with some studies claiming that between 60 and 90 per cent of olive oils sold in the US are adulterated with cheaper pomace oil or oils from other plant species such as sunflower, canola and peanut.

In 2019, a Europol-coordinated operation resulted in the seizure of 150,000 litres of low-quality oils that had been adulterated with colourants to make them appear like extra virgin olive oils, with 20 arrest made. The scam is estimated to have netted the network around $9m.

“Within one hour, the quality and authenticity of olive oils on the market can be clearly determined and counterfeits detected” using the NMR approach, according to Bayreuth University, which says information on origin can also be checked for plausibility.

“Until recently…comprehensive tests of the quality and authenticity of olive oils could only be carried out using different test procedures applied one after the other. They were therefore time-consuming and expensive, it adds.

According to Stephan Schwarzinger of the university’s Northern Bavarian NMR Centre, the test gives “an individual profile for each sample that includes all properties relevant to quality and authenticity” based on constituents such as fatty acids and polyphenols.

A comparison with existing olive oil profiles is used to check the credibility of the declaration of origin of the respective producer or trader, and the technique can be used for example to check whether the examined olive oil sample comes from Greece, Italy, or Spain.

“Cheap alternative vegetable oils are dyed green and sold as olive oil, rancid oil is mixed with good oil, or old oils are glossed over with special technologies and come back into circulation as extra virgin olive oil,” says Schwarzinger.

“These frauds damage the good reputation of this high-quality product, and could trigger a downward spiral that ultimately hits olive oil farmers via a drop in prices. And this, in turn, leads to the leaving fallow of large olive groves in the Mediterranean region with corresponding, negative ecological effects.”