Effect of Processing on PCR Detection of Animal Species in Meat Products

Although most consumers are sensitive about the origin of the meat they consume, adulteration of meat products is not uncommon. For this reason, the development of reliable methods for animal species identification in meat products is an important research priority for food scientists. Species-specific protein- and DNA- identification methods generally used for this purpose. ELISA and protein electrophoresis are used for protein, PCR is used for species-specific DNA identification. Because DNA is known to be more resistant to processing than protein, PCR methods are generally considered as more sensitive for processed foods. However, processing conditions may also degrade DNA resulting in decreased DNA quality and yield. In this study, the individual and combined effects of heat treatment and low pH on the identification of animal species in meat products by PCR were evaluated. Beef sausage mixtures containing two different amounts of meat from a secondary species (either poultry, pork, or horse) were prepared and were subjected to heat treatment (65 degrees C, 85 degrees C, and 121 degrees C) and pH adjustment (5.2 and 6.2). PCR screening for the four animal species was performed using DNA extracts of these meat samples. The results showed that, the combined effect of high temperature and low pH significantly affects the detection limit of the PCR method. Nevertheless, even low levels of adulteration can still be detected fallowing heat treatment.