Polymerase chain reaction (PCR): a possible alternative to immunochemical methods assuring safety and quality of food Detection of wheat contamination in non-wheat food products

Abstract

A rapid, sensitive and specific analysis of food samples determining wheat contamination was established using polymerase chain reaction (PCR) technology. First, primers specific for highly conserved eukaryote DNA sequences were used to prove isolated nucleic acid substrate accessibility to PCR amplification. Subsequently, a highly repetitive and specific genomic wheat DNA segment was amplified by PCR for wheat detection. This assay was tested with 35 different food samples ranging from bakery additives to heated and processed food samples. In addition, the PCR method was compared to an immunochemical assay that detected the wheat protein component gliadin. Combination of both assays allowed a detailed characterization of wheat contamination. Hence, wheat flour contamination could be distinguished from gliadin used as a carrier for spices as well as from wheat starch addition.

PCR-based DNA Analysis for the Identification and Characterization of Food Components

“…The precipitation of proteins and polysaccharides with high salt concentrations can replace the chloroform/phenol extraction steps (28). The applicability of this approach has been demonstrated for the extraction of food samples not containing meat (29). In the case of meat samples, a method for DNA extraction must yield pure DNA that does not contain inhibitors of the enzymatic amplification reaction.…”

“…CD, one of the best characterized diseases of enterocytes, is a permanent intestinal intolerance to the wheat proteins of the gliadin class and the related proteins of rye, barley and probably oats (68). The idea of research carried out in our laboratory by Allmann et al (24,29) was to detect wheat and other CD toxic cereals by PCR and to qualitatively determine the presence of these cereals in dietary foods for coeliac patients. While being aware of the fact that DNA analysis does not measure CD-triggering proteins, this molecular biological strategy was pursued because few specific and sensitive immunoassays, in which antibodies are directed against one or several CD toxic proteins, are available.…”

Celiac disease diagnosis and gluten-free food analytical control

“…The amplified product is visualized by staining with a fluorescent dye or by Southern blotting after a gel electrophoresis. The amplification of gluten-specific DNA fragments by PCR has been reported [93,94]. Normally, PCR results are only qualitative; however, by incorporating internal standards, the results provide semiquantitative measurements.…”

Detection of Genetically Modified Organisms in Foods by DNA Amplification Techniques

“…In addition, the integrity of the protein is readily affected by most food processing technologies. [15][16][17] Some commercially available GMO-detection systems, also based on the use of antibodies, use lateral-flow strips.…”