Seafood is a frequent cause of allergic reactions to food globally. The presence of
undeclared trace amounts of clam can cause allergic reactions in sensitive individuals.
Limited tools are available to test food products for the presence of traces of clam.
We report on the development of a sandwich ELISA that can detect and quantify clam
protein in food. Antisera against a mix of two commercially important clam species,
Atlantic Surf (Spisula solidissima) and ocean quahog (Arctica islandica), were raised
in rabbit and sheep. A sandwich ELISA was constructed with this antisera, and sensitivity
and specificity were evaluated. Also, model food products spiked with clam protein
were analyzed to assess the performance of the ELISA. Comparison was made with a commercially
available ELISA for crustacea. The lower limit of quantification of the sandwich ELISA
is 2.5 ppm clam protein in food samples, allowing the detection of low amounts of
clam that may trigger a reaction in clam allergic patients. The sandwich ELISA was
highly specific with cross-reactivity only noted for other molluscan shellfish (mussel
and scallop). Clam protein in tomato juice and potato cream soup was detected well
with recoveries ranging from 65 to 74% and from 74 to 113%, respectively. However
when potato cream soup was retorted, the recover fell to 20%, imposing the risk of
underestimating the clam content of a food product. A commercially available crustacean
ELISA test was not suitable to detect clam protein. The sandwich ELISA described here
is suitable for detection and quantification of clam protein in food products. Care
should be taken with food products that have been retorted as the results may be underestimated.