Species, muscle type, and formulation influence the residual concentrations of three endpoint temperature indicators in poultry products.

The objectives were to determine 1) the effect of muscle type and temperature on the concentration of lactate dehydrogenase (LDH), IgG, and serum albumin (SA) in turkey and chicken, and 2) the concentrations of these marker proteins in four turkey products processed to the USDA required endpoint temperature (EPT) of 68.3 C. Ground turkey and chicken breast and thigh meat were placed in thermal death time tubes and heated to 65.5, 68.3, 71.1, or 73.8 C. Turkey bologna, pastrami, smoked sausage, and frankfurters were cooked by a local processor to target temperatures between 65.5 and 73.8 C. Proteins were extracted and quantified by an LDH sandwich ELISA or indirect competitive ELISA for SA and IgG. Although all indicators decreased in concentration as EPT were increased, turkey contained higher (P < 0.0001) residual concentrations of the indicators than chicken. In both turkey and chicken, thigh muscle contained higher concentrations of SA (P < 0.0001) and IgG (P < 0.0001) and lower concentrations of LDH (P < 0.0001) than breast muscle at the same EPT. The concentrations of the three indicators decreased as the EPT of the four turkey thigh products were increased. At an EPT of 68.3 C, pastrami contained the lowest concentrations of SA and IgG, whereas bologna contained the lowest concentration of LDH. The LDH ranged from 441.7 ng/g bologna to 1,283.6 ng/g sausage at 68.3 C. Minimum residual concentrations of each indicator need to be established for each product before the ELISA can be used to verify processing to the USDA minimum EPT.