New laser sensor to help combat counterfeit oil

Researchers have designed a laser-based sensor that can detect counterfeit olive oil labelled as extra virgin or protected designation of origin.

The tool, described in the journal Talanta, can distinguish between apparently similar oils that present notable differences in quality.

This is possible thanks to the use of laser diodes, because the fluorescence emitted by adulterated oils is slightly different to that of pure extra virgin olive oils.

The 3D-printed tool is inexpensive both to use and to manufacture, said researchers at the Complutense University of Madrid (UCM) in Spain and the Scintillon Institute in the US.

"Other clear advantages of our tool include the possibility of conducting on-site analyses, because the equipment is the size of a briefcase and therefore portable, and of generating results in real time," said Jose S Torrecilla, a senior lecturer at the UCM.

The tool offers the olive oil sector a means to tackle a problem that generates large economic losses, researchers said.

"The quality of olive oil is recognised nationally and internationally. It is therefore necessary to protect this quality and combat the fraudulent activities carried out with increasing frequency and skill in the sector," they said.

One example of fraudulent practice, noted Torrecilla, is adulterating fresh, pure virgin olive oil with inferior, cheaper olive oil or oils of another botanical origin.

Researchers mixed single-varietal, protected designation of origin oils with other protected designation of origin oils that were past their "best before" date. All the oils were purchased from shopping centre stores.

Subsequently, mixtures were made using oils with between 1 and 17 per cent acidity that were also past their "best before" date.

Measurements were performed using the sensor, which was manufactured with a 3D printer, and an analysis was conducted of the results obtained by means of chaotic algorithms.

"This technique is available for use at any time, and only requires oils prior to packaging for quality control or after packaging to detect fraudulent brands and producers," the researchers said.