Portable sensor can sniff out fishy fish even in restaurants

Up to 30% of seafood is mislabelled when it enters the US, with unscrupulous dealers naming other species as grouper, for instance. This practice costs US fishermen, consumers and the seafood industry up to US$25 billion annually.

Scientists from the University of South Florida have developed a handheld sensor that could put a stop to this practice by assessing the RNA of seafood samples. The QuadPyre RT-NASBA rapidly and inexpensively assesses these samples using real-time nucleic acid sequence-based amplification (RT-NASBA).

The handheld instrument, which purifies and identifies the sample’s RNA, is based on a portable version of a lab-based benchtop model that the researchers had previously developed. It can be used aboard fishing vessels, dockside, in warehouses and in restaurants so consumers and seafood traders can be sure they’re getting what they pay for.

“Using the handheld 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,” said John Paul, Distinguished University Professor at the USF College of Marine Science.

“Some past assay procedures could take hours - even days - to identify samples.”

The scientists say the portable QuadPyre RT-NASBA can even detect grouper substitution on cooked fish in a restaurant, even when samples are masked by breading or sauces. This is a dramatic improvement over other techniques that have proved unreliable in similar situations.

Grouper substitution is rife in the US due to commercial quotas on grouper catches and the economic value of the fish. In 2012, US$33.5 million worth of grouper was imported into the US. The large quantity of grouper imported into the country creates plenty of opportunities for fraud.

The USF technology is being commercialised by PureMolecular, LLC, a USF spinoff company, under the name GrouperChek (trademark pending). Assays for other commercially important seafood species are being developed. Assays already exist for non-seafood problematic species such as Karenia brevis (red tide-causing organism), noroviruses and enteroviruses.

A paper describing the new technology and its application has been published in the journal Food Control.