David G. Schmale III
Virginia Polytechnic Institute and State University, Blacksburg, VA
Gary P. Munkvold
Iowa State University, Ames, IA
DETECTION OF MYCOTOXIN CONTAMINATION
Mycotoxins are commonly detected and quantified in food and feed using antibody-based assays and chromatography techniques. DNA-based methodologies for specific mycotoxigenic fungi are also used, but these assays are designed to detect the fungus and consequently can only infer potential mycotoxin contamination.
Enzyme-Linked ImmunoSorbent Assay (ELISA) is an antibody-based assay that is commonly used to detect mycotoxins. A number of commercial ELISA kits are available for aflatoxins, deoxynivalenol, fumonisins, ochratoxins, and zearalenone. This is usually a competitive assay in which the mycotoxin of interest from a sample competes with a labeled mycotoxin for a limited number of specific antibody-binding sites. Since the assay is competitive, the presence of the toxin is usually measured by the absence of color. ELISA is one of the more affordable methods for detecting mycotoxins, but the detection limit often exceeds 0.2 ppm for many mycotoxins. Commercial 96-well assays [Figure 22] and strip-tests [Figure 23] are available for many mycotoxins.
High-Performance Liquid Chromatography (HPLC) and Gas Chromatography/Mass Spectrometry (GC/MS) are two of the most widely used methods for mycotoxin detection and quantification in food safety laboratories. HPLC separates a mixture of compounds on a stationary column using a carrier solvent such as methanol or acetonitrile, and the mycotoxins are detected and quantified in the sample as they pass through a specific detector. GC/MS separates a mixture of compounds on a stationary column using a carrier gas such as helium, and the mycotoxins are detected and quantified using a mass spectrometer [Movie 3]. HPLC and GC/MS require expensive equipment and technical support, but they offer a detection limit of less than 0.05 ppm for many mycotoxins.
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