Development and Validation of Two Competitive ELISAs for the Detection of Potentially Allergenic Lupine (Lupinus Species) in Food

The paper presents two competitive enzyme linked immunosorbent assays (ELISAs) for the detection of lupine proteins in foods. The ELISAs are based on anti-lupine antibodies produced in a rabbit (IgG) and in a chicken (IgY), respectively. Cross-reactivity tests with 33 foods of plant origin revealed that both ELISAs show slight cross-reactivity (a parts per thousand currency sign1.5 %) with pecan nut. They do, however, not cross-react with 32 species potentially used in lupine containing foodstuffs. Both ELISAs detect proteins from white (Lupinus albus) and blue (Lupinus angustifolius) lupine and, with a lower sensitivity, proteins from yellow (Lupinus luteus) lupine. Matrix effects could be eliminated by diluting the sample extracts 1:10 before loading them onto the microtiter plate. The IgG ELISA allows the detection of 50 ppm white lupine flour in bread, vegetarian patties and rusk. With the IgY ELISA, lupine can be detected in vegetarian patties and bread at the 50 ppm spiking level and in rusk at the 100 ppm spike level.