Food Analysis

Tackling food fraud in the olive oil industry

Food crime is defined as serious fraud and related criminality in food supply chains, which can be seriously harmful to consumers, food businesses and the wider food industry.1 Fraudulent acts include adulteration (including a foreign substance that is not on the product’s label to lower costs or fake a higher quality), substitution (replacing a food or ingredient with another substance that is similar but inferior) and misrepresentation (marketing or labelling a product to wrongly portray its quality, safety, origin or freshness).

Analysing VOCs from olive oil samples

Giorgia Purcaro, analytical chemistry professor, and her team at the Gembloux Agro-Bio Tech Department at the University of Liège, Belgium, analyse food samples to aid the prevention of food fraud. They analysed volatile organic compounds (VOCs) from olive oil samples to build profiles that can be used to discriminate between different commercial classes of olive oil.2,3 The profiles will make it easier to identify inferior products, or cheap products being misrepresented as more expensive varieties.

Their findings may help the International Olive Council (IOC)4 identify analytical criteria for detecting fraud and determining the quality of olive oils. Currently, the IOC uses a sensory (or panel) test to classify oils in which human evaluators record their sensory responses to products being tested. “Although a panel can be repeatable, reproducibility among panels is more challenging,” says Purcaro. “Support from a sensitive analytical method would be highly beneficial to avoid misclassification of products.”

Enhancing the analytical technique

A sampling technique that is widely used for similar work is solid-phase microextraction (SPME), a solvent-free sample preparation technique in which samples are extracted by immersive or headspace sampling. However, its sensitivity is limited by the small volume of sorptive phase available for analyte extraction (typically ~0.5 μL of polydimethylsiloxane). Purcaro’s team enhanced the sensitivity of SPME by using headspace–SPME–trap with multi-step enrichment (MSE®) on the fully automated and cryogen-free Centri® sample extraction and enrichment platform to extract samples for analysis using gas chromatography–mass spectrometry (GC–MS).

Multi-step enrichment enables repeat extractions of a single sample or multiple replicate samples to be stacked onto the focusing trap inside Centri for injection into the GC for a single analysis, which maximises the sensitivity achieved.