DAILY SCIENCE

Researchers repurpose a medical tool to expose seafood fraud
A cancer-detecting device can be used to identify fish species in just 15 seconds
May 28, 2021

Researchers have discovered that a medical device used to detect cancer in humans can also be employed to detect mislabeled seafood, and other meats—with 100% accuracy. The device, which can identify the species of a sample within 15 seconds, could be a new way to intercept the significant global threat of seafood fraud, and help to make our general consumption more sustainable. 

Seafood fraud involves the substitution of one fish species (usually a pricier one) with another, cheaper species that’s difficult to distinguish visually. This isn’t just an economic problem, and a frustration for consumers who believe they’re getting a particular type of fish; it’s also environmentally destructive. 

By casting a veil over the true identity of fish, mislabeling makes it easier for illegally-caught seafood to find a market, and for this activity to continue unhindered. Mislabeled fish also make it more difficult to accurately track fish stocks and levels of consumption. What’s more, fraudulent fish can undermine consumer efforts to eat more sustainably, if the species they think they’re getting is actually an entirely different—possibly more threatened—fish. 

Studies suggest that seafood fraud is rampant globally, with estimates showing that anywhere between 20% and 50% of fish is mislabeled in shops and restaurants around the world. With fish now being the most globally-traded food, and with consumption rising globally, mislabeling presents a ticking time bomb for fisheries conservation. Unless, of course, we get better at discouraging this illegal activity, which is where the new device comes in.

Currently, regulators use polymerase chain reaction (PCR) tests—an industry standard that relies on tiny segments of DNA to decipher the identity of products along supply chains. But the researchers on the new study turned to another existing medical device, and applied it to this sustainability problem, in the hopes that it could provide a more efficient alternative to the standard. 

The device, called a MasSpec Pen, is a dinky, hand held instrument that uses a technique called mass spectrometry to identify molecules in a substance that can reveal information about the identity of that sample. The pen tip produces a droplet of solvent that touches the sample surface; this then gently extracts molecules from the flesh, and feeds them back up the shaft of the pen and into a machine. There, it undergoes analysis that breaks down the chemical components of the molecular mix. 

The researchers sampled a range of meats —from grass-fed and grain-fed beef, to venison, and five types of commercially important fish in the US: cod, halibut, Atlantic salmon, sockeye salmon, and steelhead trout. From these various samples, the pen isolates several types of compounds, including taurine, xanthine, and carnosine. In each species, the variety, quantity, and combination of these compounds will be different, and because animals assimilate these through diet and habitat, they can therefore provide informative clues about the identity of the creature that they came from. 

Using this information, the research team was able to draw up a set of unique profiles for each type of meat, using these to build a model that could identify species by these molecular cues. When they then tested this model on a separate set of samples, the MasSpec Pen was able to detect these with a striking 100% accuracy. 

The tool’s sensitivity is what makes it powerful: the pen was able to distinguish grass-fed from grain-fed beef, and both of these from venison. But perhaps most compellingly, it could tell each of the five fish species apart. This was also a powerful proof of principle, because all five fish species are common candidates of fish fraud: cod and halibut look similar and are frequently exchanged, as is true for trout and the two salmon species.

The MasSpec Pen doesn’t damage the fillet at all. But then neither does PCR technique—so why not just stick with the tools we already have? One huge advantage is that the handy pen can identify the sample 720 times quicker than the standard PCR tests used in the food industry, which take around three hours to spit out a result. 

What’s more, the researchers think that the molecular basis of their pen tool presents an opportunity to fine tune the modeling to detect ever more nuanced features of a fish’s identity—drawing perhaps on further details about its diet, or its environment—to make the tool more accurate and expand its use to more species. 

Next, they’ll be working on making the MasSpec Pen more portable, so it can be carried into the field and applied more widely in various contexts. To truly tackle seafood fraud, the more tools we have, the better—and hopefully this one will move us an inch closer to more sustainable global fisheries. 

Gatmaitan et. al. “Rapid Analysis and Authentication of Meat Using the MasSpec Pen Technology.” Journal of Agricultural and Food Chemistry. 2021. 

Image ©Mikeaubry | Dreamstime.com

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