The melamine crisis in milk in 2008 in China was a turning point for food fraud due to the large number of illnesses and several infant deaths. The perpetrators added melamine to diluted milk to increase the protein content via nitrogen from the melamine. After food companies began testing for melamine, the perpetrators moved on to urea and other compounds to falsify the protein content—an important quality indicator. This has led to the development of nontargeted testing methods to detect food fraud in cases where the user doesn’t know what adulterants may be present in the food, noted Kenny Xie, scientific liaison at U.S. Pharmacopeia (USP), during the Tuesday morning session on “Non-Targeted Methods and Application of Food and Dietary Supplement Adulteration Detection: Challenges and Future.”
According to Xie, food fraud is the intentional misrepresentation of the true identity or contents of a food ingredient or product for economic gain. Up to 10% of the food supply may contain fraudulent ingredients, which are detected only 4% of the time.
The first step in conducting nontargeted testing is to create a reference set of samples for comparison and similarity assessment with the unknown samples. Since some products may contain natural variabilities due to seasonal changes and geography, the reference set should contain numerous samples. In addition to the unknown samples, food companies can also spike their products with contaminants to compare with the reference set to anticipate potential fraud scenarios in the future.
Based on its extensive work on nontargeted methods, USP has developed a guidance document that addresses the collection and analysis of reference samples, development and validation of the nontargeted testing statistical models, monitoring and maintenance, as well as advice on abnormal samples handling. The document is published in Food Chemicals Codex.