Immunological methods in food microbiology

Abstract

Microbial contamination of foods can now be determined using, unmunochemical methods based on the principle of antibody and antigen interaction. Assay methods in use include radioimmunoassay (RIA), enzyme linked immunosorbent assay (ELISA), affinity chromatography, immunofluorescence and agglutination. Such methods have been applied for the detection of microbial metabolites, e.g. mycotoxins which can now be determined at levels as low as a few parts per billion (ppb = μg kg −1) to be present in a food sample such as peanuts in a matter of minutes using immunological methods. Bacterial enterotoxins have long been detected in foods using immunoassays: however, recent results of new technologies have allowed for the routine analysis of suspected contaminated foods using simple methods. The presence of viable bacteria such as Salmonella in foods has previously only been achievable after isolation of the bacterium. Now, however, with the advent of more specific and sensitive methods such as the sandwich ELISA and latex agglutination, it is possible to establish the presence or absence of these pathogenic bacteria from a mixed broth culture of the food sample several days prior to traditional testing methods. Thus, when compared with conventional methods immunoassays offer similar detection limits and confidence levels. Furthermore, they simplify sample preparation procedures in relation to extraction of metabolites and growth of micro-organisms.