SPECIES, MUSCLE-TYPE, AND FORMULATION INFLUENCE THE RESIDUAL CONCENTRATIONS OF 3 END-POINT TEMPERATURE INDICATORS IN POULTRY PRODUCTS

The objectives were to determine 1) the effect of muscle type and temp erature 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 r equired endpoint temperature (EPT) of 68.3 C. Ground turkey and chicke n breast and thigh meat were placed in thermal death time tubes and he ated 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 t emperatures between 65.5 and 73.8 C. Proteins were extracted and quant ified by an LDH sandwich ELISA dr indirect competitive ELISA for SA an d IgG. Although all indicators decreased in concentration as EPT were increased, turkey contained higher (P < 0.0001) residual concentration s of the indicators than chicken. In both turkey and chicken, thigh mu scle 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 EP T of 68.3 C, pastrami contained the lowest concentrations of SA and Ig G, 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. Mini mum residual concentrations of each indicator need to be established f or each product before the ELISA can be used to verify processing to t he USDA minimum EPT.