Temperature Histories at Critical Points and Recommended Cooking Time for Whole Turkeys Baked in a Conventional Oven

Abstract

Time-temperature histories and cooking times were determined for turkeys baked at 162.8°C from 4.44°C to an endpoint of 82.2°C in the thigh joint or breast. Turkeys (128) in five weight classes from 5.9 to 10.8 kg (0.9 kg increments) were equally divided into fresh, frozen, stuffed, unstuffed, and cooked shielded or unsheilded groups. The slowest heating point was either the wing joint or stuffing geometric center. Cooking time for unsheilded turkeys was 155 min plus 11 min/kg, unstuffed, and 200 min plus 8.8 min/kg, stuffed. Median cooking loss was 23%. Shielding of breasts prolonged cooking time. The cooking endpoint of 82.2°C in the thigh joint provided adequate lethality against Salmonella in the slowest heating points of both stuffed and unstuffed birds.were below 71.1°C. Thus, Lee (1993) considered pop-up indicators to be unsatisfactory for establishing the cooking endpoint especially when birds weighed more than 8.54 kg.Our objectives were to: (1) Determine the heat lethality against Salmonella delivered to critical points (slowest heating) in whole baked turkeys by continuously monitoring temperature (2) Develop time guidelines for baking turkeys at 162.8°C oven temperature;(3) Determine if there is a reliable location for placement of a commercial pop-up timer on the breast, to ensure adequate heat lethality against Salmonella in all points. MATERIALS & METHODS Preparation of turkeys for cookingThree self-cleaning convection ovens (Model 130, Daycor, Pasadena. CA) were used. The ovens were operated in the bake function with the convection function disabled. Before the experiment, the oven temperature controllers were calibrated by setting them to 163.8°C and the ovens were heated continuously for 4 h. The oven temperature sensing element remained as provided by the manufacturer. The oven temperature indicator was calibrated against a mercury-in-glass thermometer in the oven. To dampen oven temperature oscillation as the heating element cycled, the thermometer bulb was inserted into a 3.2 cm dia by 10.2 cm aluminum cylinder. Temperature indicated by the thermometer was made to equal that displayed on the oven front panel at the set point by adjusting the calibration pads on the oven front panel. Measured average temperature was that displayed on the front panel ±0.5°C. A copper constantan thermocouple inserted in the geometric center of a 1.3 cm ∞ 2.5 cm ∞ 3.8 cm Teflon ® block attached

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“…Most research has focused on temperature history. Chang, Carpenter, and Toledo (1998a) presented temperature histories at various locations in a whole turkey during roasting and found that the slowest heating point located at the middle of the breast. Chang, Carpenter, and Toledo (1998b) temperature history for a roasted turkey using a twodimensional unsteady state heat and mass transfer model.…”