ABSTRACT
Residual glutamic-oxaloacetic transminase (GOT) activity in laboratory-prepared samples of white and dark chicken meat heat treated to end-point temperatures (EPTs) of 70 to 75°C were determined. Declines in activity with increasing EPTs occurred in both tissue types; activities were significantly higher (P < 0.05) in dark meat samples at all EPTs except 75°C. Regression coefficients of GOT activities on EPTs of the laboratory prepares sampled were rearranged to estimate EPTs for poultry products obtained from a commercial processing plant. Desired EPTs of the commercial products were 71 and 74°C for white and dark meat, respectively. Product EPTs estimated by measurement of residual GOT activities were 74 to 75°C. Measurement of residual GOT activity appears to be a rapid, accurate means to estimate EPTs in commercially produced poultry products of uniform size and thickness.
ABSTRACT
The influence of cooking end-point temperatures (EPTs) of 62.8, 66.7, 67.8, 68.9, 70.0, 71.1, 73.9, and 76.7°C on residual creatine phosphokinase (CPK) activity in laboratory prepared model systems of ground chicken and turkey breast meat was determined. CPK activity was also assayed in commercially prepared chicken, turkey, and meat products using a Sigma #661 CPK test kit. Three tenths milliliter of 0.9% saline extracts obtained from the chicken, turkey, and meat products was substituted for 0.3 ml serum specified in the test kit procedure. For the model samples, there was a marked decrease in CPK activity as EPT increased from 66.7 to 76.7°C; however, model samples heated to 76.7°C did retain low amounts of CPK activity. In general, very low levels of CPK were found in commercially prepared chicken and turkey products (0 to 10.6 Sigma units/ml). Results of CPK activity in commercially prepared meat products would indicate that the test is product dependent, with values ranging from zero for beef franks to 258 Sigma units/ml for hard salami. Thus, while CPK activity may be useful for detecting cooking EPT for quality control purposes, it should not be used as a regulatory procedure where experience with the specific product is not available.
ABSTRACT
The variables, sample size and temperature of cooking media, were tested to determine their influence on myoglobin content and glutamic oxaloacetic transaminase (GOT) activities in bovine semimembranosus tissue thermally processed in a model heat treatment system. Data were obtained from 2.9 and 5.5 × 8.0 cm samples that were thermally processed to end-point temperatures (EPTs) of 62.8, 71.1 and 79.4°C in a water bath that exceeded EPTs by 2 and 20°C. Myoglobin denaturation differed (P < 0.05) by EPTs within samples, by sample size at the specified EPTs and by temperature of the heating media used to attain the EPTs within sample sizes. Similar variations at this probability level were observed in the analyses for residual GOT activities of the samples. Data indicate the inadequacies of analysis of these parameters in model systems that do not duplicate the actual process being evaluated.
