Detection of Krill in Foods Using Real-Time PCR

FDA has received consumer complaints about food products, most notably sardines, containing krill as an undeclared crustacean shellfish allergen. The Food Allergen Labeling and Consumer Protection Act (FALCPA) requires that food products containing crustacean shellfish be labeled with the type of crustacean. Available antibody-based allergen detection assays, which detect proteins, do not distinguish crustacean type. Real-time PCR assays, which detect DNA, can differentiate type of crustacean. The purpose of this work was to develop and evaluate a real-time PCR-based method for the detection of krill contamination in foods, with a focus on detection in sardines. A previously developed shrimp assay was adapted to specifically detect krill through modification of primer and probe sequences targeting the 16S ribosomal RNA gene of mitochondria. Two different sets of modified primer and probe sequences were found to work equally well, yielding specific detection of krill in sardines with lower limits of detection at 0.1–1 mg/kg and linearity over 7–8 orders of magnitude. While krill is not necessarily a close taxonomic relative of shrimp, this work has shown that minor changes in shrimp primers and probe were nonetheless able to yield an effective and specific krill assay.