DNA Barcoding Revealed Mislabeling and Potential Health Concerns with Roasted Fish Products Sold across China

Abstract

Roasted fish fillet is a popular snack food in the People's Republic of China, and the market appeal can be reflected by the high price, which exceeds 330 RMB/kg in some cases. However, the labeled fish common name generally cannot be connected with a particular species, and the processing treatments make it a challenging task to identify fish species based on morphological characteristics. This study used full DNA barcoding and mini-DNA barcoding for species identification of 202 specimens sorted from 64 roasted fish fillet products sold across China, which belonged to 32 distinct brands and claimed 16 fish common names on the label. Given the absence of a harmonization in defining these common names in China, scientific literature and the Latin-Chinese dictionary of fish names (http://fishdb.sinica.edu.tw/) were consulted to define at least the family for each common name, and an identified species outside the expected family was determined to be mislabeled. Results highlighted a high mislabeling rate of 75.5%. Even worse, fish species were identified as belonging to multiple families, not only from several products of the same brand under the same common name but also from several specimens sorted from the same product. Moreover, a health issue was highlighted by the identification of toxic Tetraodontidae species from one product. To protect the consumers from economic loss and even health risks, we recommended amendments to existing legislation and the compilation of a list of acceptable market names for fish species in China. Meanwhile, DNA barcoding is a powerful tool in fish forensics, and we recommended the use of this technique to assure the accurate species labeling of fish products. HIGHLIGHTS

Development of a rapid method for codfish identification in processed fish products based on SYBR Green real‐time PCR

“…More specifically, U. japonicas is a small‐sized fish with low commercial value, and the mislabelling as codfish could lead to illegal profit. While great health concern with several species of Lagocephalus has already been reported (Xiong et al , ), the circulation of Lagocephalus species is strictly controlled in China, which, however, could be avoided by mislabelling as codfish. Finally, R. ectenurus and L. litulon products sold as codfish also represent an improved access to the market, given the great popularity and preference towards codfish in China (Xiong et al , ).…”

DNA barcode by flossing through a cylindrical nanopore

“…The barcodes are nally estimated by multiplying the calculated 2step velocity in eqn (7) above by the tag time delay as…”

“…Though researchers relied on DNA sequencing techniques for the identification of unknown species for a long time, in 2003, Hebert et al 2 proposed the mitochondrial gene (COI) region barcoding to classify cryptic species 3 from the entire animal population. Since then, several studies have shown the potential applications of barcoding in conserving biodiversity, 4 estimating phyletic diversity, identifying disease vectors, 5 authenticating herbal products, 6 unambiguously labeling the food products, 7,8 and protecting endangered species. 4 Traditional sequencing methods based on chemical analysis are still been widely used in the biological community to determine the barcodes.…”

One‐step triplex high‐resolution melting (HRM) analysis for rapid identification of Atlantic cod (Gadus morhua), Alaska pollock (Gadus chalcogrammus) and haddock (Melanogrammus aeglefinus)

“…Authentic samples of eight Gadiformes species and seventeen non-Gadiformes species commonly found on the market were used for specificity evaluation of the newly established triplex HRM assay in the present study, summarised in Table 1. All of them were obtained either form our previous studies (Xiong et al, 2020a(Xiong et al, , 2018(Xiong et al, , 2019, from the official food control authorities, or from the local supermarkets and morphologically identified by professionals. Moreover, DNA barcoding method (Handy et al, 2011) (data not shown) was used to cross-confirm the identity of all fish samples and the obtained sequences have been submitted to Genbank database (Table 1).…”