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 instr umental and visual color of ground beef, pH was adjusted to 5.2-6.4, sample s were heated at 0.7 degrees C or 3 degrees C/min to 55, 60, 65, 70, 75 or 80 degrees C in a water bath. Cooking rate had no effect on cook loss, inst rumental 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 increa sed by adding the calculated percentages of metmyoglobin and/or deoxymyoglo bin to the regression models. The predicted sensory brownness score (0 = ve ry pink, 7.5 = intermediate pink/brown, 15 = intense brown) for samples wit h pH 5.75 cooked to 70 degrees C was 9.75. Samples with a pH of 5.5 achieve d this brownness score at 67 degrees C. Samples with a pH of 5.2 achieved t his brownness at 58 degrees C. (C) 1999 Elsevier Science Ltd. All rights re served.