Grouper are one of the most economically important seafood products in the state of Florida and their popularity as a high-end restaurant dish is increasing across the U.S. There is an increased incidence rate of the purposeful, fraudulent mislabeling of less costly and more readily available fish species as grouper in the U.S., particularly in Florida.
So far that's likely no news to readers of this blog and the problem is unfortunately not limited to grouper species. Two years ago a group based at the University of South Florida developed a generic grouper assay that was capable to detect the majority of the grouper species listed on the US FDA Seafood List and it did so in 90 minutes.
The alternate technology was termed nucleic acid sequence-based amplification (NASBA). It is similar to PCR in that both involve the amplification of specific nucleic acid sequences via enzymatic reactions. However, NASBA targets RNA rather than DNA, and it is carried out at a constant temperature of 41 °C whereas PCR requires thermal cycling within large temperature ranges up to 95°C which also requires specific thermostable enzymes. As target the authors choose 16S rRNA as this form of RNA tends to be more resistant to degradation than messenger RNA (mRNA), which is the form of DNA Barcode RNA in tissue cells. It also seemed to be better suited for the grouper species the authors were targeting. However, they also made clear that COI might work better for other species and for fish identification on a larger scale.
Now, just two years later the same group presents their next invention: A handheld sensor assay for grouper identification based on the NASBA protocol. The QuadPyre RT-NASBA, assays the fish samples using a real-time version of the earlier procedure (RT-NASBA). The handheld instrument that purifies and identifies the sample's rRNA is a portable version of the lab-based benchtop model previously developed.
Using the hand-held device, a complete field assay, potentially carried out at the point of purchase, requires fewer than 45 minutes for completion and can be performed entirely outside of the lab.
The technology is already being commercialized by a spin off company called PureMolecular, LLC under the name GrouperChek (trademark pending). Is there a market for this. I do think so. It's estimated that up to 30% of the seafood on the U.S. market is fraudulently mislabeled, bilking fishermen, the seafood industry, and consumers for an estimated $20-25 billion annually.
We believe there is heightened interest for a portable, uncomplicated technology such as the QuadPyre RT-NASBA assay that allows for rapid on-site screening of genetic material from seafood similar to point-of-care testing devices used for rapid diagnosis in clinical settings (Ahmad & Hashsham, 2012). What is more, the format of the handheld heated fluorometer allows for potential implementation of alternate RT-NASBA assays utilizing oligonucleotide sets to target other commercially important finfish groups such as snappers and tunas, which had the highest mislabeling rates according to the aforementioned Oceana investigation (Warner et al., 2013). Presenting personnel in seafood purchasing and regulation of such commerce with rapid and portable forensic technologies such as the one presented here will help close inspection gaps to better combat seafood mislabeling fraud.