Detection of milk allergen protein trace in food products by sandwich-antibody enzyme linked immunosorbent assay.

Here we report a new method that sandwich-antibody enzyme linked immunosorbent assay (ELISA) was successfully used to detect milk allergen protein in food products. The Balb/c mice were immuned with the extracts of milk allergen proteins and the highly-titrated polyclonal IgG antibodies against them were isolated for our immunoblotting assay. The total milk allergen protein was extracted and further analyzed by SDS-PAGE. Our results indicated that the standard curve is linear with milk allergen protein concentration from 25 to 1000 ng/ mL, and the detection limit is 25 ng/mL of milk allergen protein. Food products from markets were tested using this method. We found that 10 foods were detected with the milk allergen protein, which were consistent with the food allergen labels from their manufactures. However, one food without food allergen label was detected to contain milk allergen protein and the other one without food allergen label was tested to contain no milk allergen protein. Thus we concluded that sandwich-antibody ELISA could be used to detect milk allergen in food products.