Virgin olive oil authentication using fingerprint technique

Food fraud in the olive oil industry is becoming increasingly common, especially when it comes to the origin and varieties of a product. Now, a team in Spain has presented a new authentication tool to check the geographical origin of virgin olive oil as a control on the quality, tradition and product linked to the territory.

The team, from the Faculty of Pharmacy and Food Sciences, Torribera Food and Nutrition Campus and the Institute for Nutrition and Food Safety Research (INSA) of the University of Barcelona, developed the new tool to provide an official authentication method that could be applied at different geographical scales.

The methodology, which has been published in the journals Food Chemistry and Food Control, enables the discrimination between virgin olive oils produced in the European Union and those that are not. The geographical authentication strategy is based on the analysis of sesquiterpene hydrocarbons — organic compounds formed by three isoprene units — which proved to be good origin markers for olive oil.

“The cornerstone of an efficient authenticity tool is for it to be based on robust analytical markers. In the case of the geographical authentication of the virgin olive oil, the markers depend largely on the variety of olive tree and the area where it grew, without being significantly influenced by other factors related to the process of extracting or preserving,” notes researcher Beatriz Quintanilla-Casas (UB-INSA), first author of the studies.

“The sesquiterpene hydrocarbons present in the virgin olive oil meet the requirements from above, and are robust geographical markers of this commercial product. Also, since they are semi-volatile compounds, they can be easily analysed with a widely used analytical tool — mass spectrometry-coupled gas chromatography — with a previous solid-phase microextraction, a relatively quick and automated procedure which does not require the use of solvents.”

The new protocol can authenticate virgin olive oils through a fingerprint, which works similarly to the recognition of people using fingerprints. “In this case, the sesquiterpene fingerprint is used for the development of geographical discrimination models that enable us to identify those oils that show an analytical signal very different from those considered as reference oils,” said researcher Stefania Vichi.

“Traditionally, reference methods for the authentication of products are based on the determination of one or a few compounds, so that the legal limits are set to decide whether the product meets certain specifications. Non-directed methods — like fingerprinting — enable using all the available analytical data, instead of focusing on certain compounds like traditional methods do,” noted researcher Alba Tres.

The process of transforming an analytical method into an official methodology with a legal validity is slow and complicated, especially if the provided innovation is based on an untargeted approach. In the case of the new technique, created in collaboration with the virgin olive oil producers, the first potential users would be the inspection and control laboratories, certification entities and marketing companies of the olive oil sector.

Image credit: ©stock.adobe.com/au/Dušan Zidar