Source: NOAA

Are you sure that’s halibut on your plate? You may have ordered red snapper, but is that actually what you’re eating?

Fish fraud—the substitution of a cheaper species for the more expensive one advertised—is a global problem. Fish can be mislabeled at numerous points from the docks to processing plants to retail establishments. The result is that a consumer could unwittingly be dining on rockfish instead of red snapper or tilapia instead of grouper. This practice undermines environmental regulations limiting overfishing and can introduce unexpected health risks in the form of allergens, toxins and parasites.

Some progress has been made by using DNA testing and barcoding to differentiate between fish species, but it can be costly and time-consuming. Since matrix-assisted laser desorption/ionization time-of-flight (MALDI–TOF) mass spectrometry has been effectively used to differentiate microbial species, researchers applied the method to develop a database containing protein patterns of common food fish prone to substitution.

The database devised by researchers from Intertek Food Services GmbH (Bremen, Germany) currently comprises 54 fish species, including salmon, trout, swordfish and other fish commonly sold in grocery stores or restaurants. DNA barcoding, a process that uses a partial DNA sequence from a mitochondrial gene, was used to confirm findings. In some cases, they were only able to identify a sample’s genus rather than the exact species. The researchers conclude this level of identification could be enough for food scientists to broadly detect fish suspected of being an imposter.