Spain: Identifying shellfish by their mitochondrial DNA

Research lead

Scientists from the University of Santiago de Compostela and the Institute of Marine Research, Spanish Council for Scientific Research, have analysed 41 commercial products which included prawns or langoustines, and found that 24.4 per cent of the labels carried the wrong species name, and that information is incomplete in 39 per cent of cases.

The researchers have patented a molecular method that enables this type of shellfish species to be distinguished by its mitochondrial DNA.

Jorge Borros, professor at the Laboratorio de Higiene, Inspección y Control de Alimentos (Laboratory for Hygiene, Inspection and Monitoring of Food), at the Spanish Council for Scientific Research, said that identifying crustaceans and is more or less impossible to achieve in the peeled product.

“This makes it difficult both for people working in the industry and consumers to be sure that the labelling is correct.” As a result, some companies resort to a generic labelling system, simply specifying langoustines or prawns.

Each species has its own taste, colour, odour and feel, which determine their price and commercial value. Barros explains, “In Japan they will pay $100 per kilo for certain types of langoustines,” adding, “For this reason, if there was a way for species to be determined it could be very useful for both the industrial sector and the authorities too.”

The authentication method developed by the scientists has been patented and enables more than 20 species of langoustine to be differentiated. In addition, the researchers have developed a specific technique for identifying the two most commercially important species, the giant tiger prawn, Penaeus monodon, and the Pacific white shrimp, Litopenaeus vannamei. Both species are widely farmed in Central America and South East Asia, and represent almost 80 per cent of the total volume of farmed langoustines marketed worldwide.