Species differentiation of heated meat products by DNA hybridization

A method for quantitation of pork in heat-treated meat products is described. The procedure involves isolation of DNA from meat samples followed by a determination of the average size of DNA fragments by agarose gel electrophoresis. The DNA is then immobilized on nylon membranes and hybridized with a (32)P-labelled probe made from genomic porcine DNA. The signal intensity from filter-bound DNA probe is determined by laser densitometry of the autoradiographs. Functional relationships between the signal intensity and the fragment size of the DNA as well as signal intensity and the amount of pork DNA have been established. Pork DNA can therefore be quantified using DNA standards with the same fragment size as the actual sample DNA. Samples of known composition and heat treatment have been investigated. The detection limit has been determined to approximately 0·1% pork in beef whereas for heat-treated samples the detection limit has been determined to approximately 0·5% pork in beef. Examples are given in which the present method has been applied on commercial canned and cold-stored foods. The results of the investigation indicate that the DNA-hybridization technique applying (32)P-labelled probes can be used for quantitative determinations in quality control of heat-treated meat products.