Multispecies seafood products

Trade globalization coupled with the substantial shift in people lifestyle led to a radical change of consumer food demand during the last two decades.  In particular, consumers moved towards products characterized by both a convenient and “time-saving” preparation  such as ready to eat and ready to cook products. Among the seafood products, surimi, fish sticks, fish cake, fish balls, salads ecc. are included in this category. In many cases they are composed by a mix of different seafood species, belonging to fish category but also to crustaceans and molluscs. As regards the labeling rules, in accordance with the current European regulation, it is interesting to note that regulation on seafood labeling and traceability (Regulation (EU) 1379/2013), that imposes the declaration of essential information such as the commercial and scientific denomination of the species present in the product, is not applied to these products. For this reason, processors of are not required to declare the species used on the label and this aspect may undoubtedly make fraudulent species substitution easier. Over the last years there has been an explosion in the use of FINS (Forensically Informative Nucleotide Sequencing) DNA barcoding techniques as a tool for species identification in food inspection. Although this method is reliable for the identification of single species, it has been proved poorly effective for the detection of species within mixed foods. This shortcoming could represent a limit for food inspection activities aimed at maximize consumer safeguard. In this regard, with the development of innovate metabarcoding techniques, Next Generation Sequencing (NGS), through a clonal sequencing phase, could allow to detect different species in a mixed sample. To date, few studies applying NGS have been conducted in the food inspection field, especially on multispecies seafood products.

In the first study, surimi-based products were analyzed through DNA-barcoding technique in order to  assess the level of degradation and the amplificability of DNA using universal primers. The selection of suitable universal primers with high fish species coverage undoubtedly represents a fundamental preliminary step for NGS metabarcoding techniques. For this reason, in the second study the performance and the potential utilization of 14 universal primer pairs amplifying fragments of  different length from 16SrRNA, COI and cytb genes of fish and cephalopod species were assessed. Species used in surimi preparation were chosen as target. Finally, metabarcoding NGS techniques were practically applied to artificial DNA mixture samples containing different fish and cephalopod species (among those most utilized in surimi preparation) in various percentage. In the same work, metabarcoding was applied on commercial surimi-based products collected on International market. This study was done in collaboration with the Instituto de Investigaciones Marinas (IIM-CSIC) of Vigo (Pontevedra, Spain).

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PUBBLICATIONS

Giusti, A., Armani, A., & Sotelo, C. G. (2017). Advances in the analysis of complex food matrices: Species identification in surimi-based products using Next Generation Sequencing technologies. PloS one, 12(10), e0185586.

A. Giusti, L. Tinacci, C. G. Sotelo, M. Marchetti, A. Guidi, W. Zheng, A. Armani (2017). Seafood identification in multispecies products: assessment of 16srRNA, cytb and COI universal primer efficiency as preliminary analytical step for setting up metabarcoding Next Generation Sequencing (NGS) techniques. J Agric Food Chem. 2017 Mar 14. doi: 10.1021/acs.jafc.6b05802.