The study, which collected 153 roasted fish fillet products from 30 commercial brands sold as ‘Xue Yu’ in China and identified them using DNA and mini-DNA barcoding, revealed an alarming misrepresentation rate of at least 58% — even using the least stringent definition of ‘Xue Yu’.
The samples were purchased from local markets in the provinces of Liaoning, Shandong, Jiangsu, Zhejiang, Fujian, Guangdong, Hubei and Sichuan, as well as Shanghai.
DNA analysis found the sampled fish to be from multiple species.
Only 42% of the fish samples were identified as belonging to Gadiformes, of which Xue Yu is believed to be from, while the others were Scorpaeniformes, Tetraodontiformes and Lophiiformes.
Once again this study highlights how seafood authentication and truthful representation of food labels in China currently count among the most critical concerns for the industry.
DNA analysis results and health implications
Given disputed definitions of Xue Yu, DNA analysis of the samples were assessed using three different definitions. Mislabelling of the products ranged from 58% for the first two definitions, and 100% for the strictest definition.
The researchers said this was not surprising as, globally, seafood species adulteration or fraud is rife. In China, despite some improvements, the fishery sector still suffers from great legislative and managerial shortcomings. Specific provisions for the labelling of fishery products and an official reference list of seafood trade names are still lacking.
What was more alarming was, among all the samples analysed and identified, the Lagocephalus spp. genus of fish was found in 37 samples. This genus includes the deadly pufferfish.
The researchers stated that an explanation could be that sellers deliberately mislabelled roasted Lagocephalus spp. as Xue Yu in order to overcome consumers' resistance to it or to augment the taste of the product.
Conclusion & recommendations
The researchers stated that seafood species adulteration is getting worse due to rising global seafood trade, particularly of processed seafood products, depleted fishery resources and the absence of policies governing seafood labelling, as well as inadequate enforcement in some countries.
The study recommends the construction of a clear legal framework for the management of the entire seafood supply chain and stringent enforcement of regulations by the China authorities.
Recent advancements in molecular biology have also contributed greatly in suppressing seafood species adulteration. As evidenced in this study, the power of DNA in determining even closely-related seafood species is clear.
Consumers are also encouraged to promote sustainable fishing and production by choosing sustainable options.
Source: Food Control
“Multiple fish species identified from China's roasted Xue Yu fillet products using DNA and mini-DNA barcoding: Implications on human health and marine sustainability”
Authors: Xiong, Lili Yao, Xiaoguo Ying, Lixia Lua, Lisa Guardone, Andrea Armanid & Xiaohui Xiong.