Cooking rate, pH and final endpoint temperature effects on color and cook loss of a lean ground beef model system

To assess the effects of pH, heating rate and endpoint temperature on instrumental and visual color of ground beef, pH was adjusted to 5.2-6.4, samples were heated at 0.7°C or 3°C/min to 55, 60, 65, 70, 75 or 80°C in a water bath. Cooking rate had no effect on cook loss, instrumental or visual color. Regression equations for linear, quadratic and/or cubic effects of pH and/or endpoint temperature were significant for most color indices. Amount of variance explained by the model and R(2) was increased by adding the calculated percentages of metmyoglobin and/or deoxymyoglobin to the regression models. The predicted sensory brownness score (0=very pink, 7.5=intermediate pink/brown, 15=intense brown) for samples with pH 5.75 cooked to 70°C was 9.75. Samples with a pH of 5.5 achieved this brownness score at 67°C. Samples with a pH of 5.2 achieved this brownness at 58°C.