Immunoassays

Almost any organic molecule in food can be determined using immunoassays as long as the specific antibodies are available. The remarkable selectivity and sensitivity of these assays are the result of the strong binding affinity between antibodies and their antigens. In the food analysis area, immunoassays are widely used for chemical contaminants analysis, identification of bacteria and viruses, and detection of proteins in food and agricultural products (e.g., allergens and meat species content, seafood species identification, and detection of genetically modified plant tissues). This chapter on immunoassays compares and contrasts direct vs. indirect assays and competitive vs. noncompetitive assays. It describes the principles and procedures for enzyme-linked immunosorbent assays (ELISA), lateral flow strips, and immunoblots (Western blot and dot blot). Methods covered are compared and contrasted, giving advantages, disadvantages, and applications. Also described are immunoaffinity purification and its applications.