Identification and semi-quantification of Atlantic salmon in processed and mixed seafood products using Droplet Digital PCR (ddPCR)

• Published in: Food and Chemical Toxicology
• Main Authors: Deconinck, Dumas, Hostens, Kris, Taverniers, Isabel, Volckaert, Filip A.M., Robbens, Johan, Derycke, Sofie
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2021
• Subjects: Science & Technology; Life Sciences & Biomedicine; Food Science & Technology; Toxicology; Seafood; Mixed and processed food products; Rhodopsin; Salmonid DNA; Food fraud; DNA; SUBSTITUTION; CHAIN; FISH; ONCORHYNCHUS; TROUT; MEAT; Animals; Cooking; Food Contamination; Freezing; Limit of Detection; Oncorhynchus mykiss; Polymerase Chain Reaction; Salmo salar; 0908 Food Sciences; Food Science; 3006 Food sciences; 3214 Pharmacology and pharmaceutical sciences; Pacific; Atlantic salmon
• Online Access: https://lirias.kuleuven.be/handle/20.500.12942/693706; https://hdl.handle.net/20.500.12942/693706; https://lirias.kuleuven.be/retrieve/659570; https://doi.org/10.1016/j.fct.2021.112329; https://pubmed.ncbi.nlm.nih.gov/34116106

Fishery products are often subject to substitution fraud, which is hard to trace due to a lack of morphologic traits when processed, gutted, or decapitated. Traditional molecular methods (DNA barcoding) fail to identify products containing multiple species and cannot estimate original weight percentages. As a proof of concept, an Atlantic salmon (Salmo salar) specific ddPCR assay was designed to authenticate mixed food products. The method proved to be specific and able to accurately quantify S. salar when using DNA extracts, even in the presence of DNA from closely related salmon species. The ddPCR estimates correlated well with the percentage of S. salar in artificially assembled tissue mixtures. The effect of common salmon processing techniques (freezing, smoking, poaching with a "Bellevue" recipe and marinating with a 'Gravad lax' recipe) on the ddPCR output was investigated and freezing and marinating appeared to lower the copies detected by the ddPCR. Finally, the assay was applied to 46 retail products containing Atlantic or Pacific salmon, and no indications of substitution fraud were detected. The method allows for a semi-quantitative evaluation of the S. salar content in processed food products and can rapidly screen Atlantic salmon products and flag potentially tampered samples for further investigation. sponsorship: We thank Miguel Faria from ICETA for providing salmonid tissues for the assays and Remigiusz Panicz for providing us with the Polish retail samples. We also thank Koen Degelas and Caroline Weydert (BioRad) and Mieke Dhondt (ILVO) for their help with running ddPCR reactions. Additionally, we would also like to thank the reviewers for this study for their insightful input. This project has received funding from the European Union's Horizon 2020 funding programme. Grant Agreement no. 773400 (SEAFOODTOMORROW) . This output reflects the views of the author (s) and the European Commission cannot be held responsible for any use that might be made of the information contained therein. (European ...