Sensory and Objective Evaluation of the Color of Pork Longissimus Dorsi Muscle Heated to 155° and 170°F

The color of longissimus dorsi muscle of 4-6 rib pork roasts was evaluated by sensory tests, by color reflectance, and by myoglobin content, after heating to 155° and 170°F. The color of the raw muscle of 8-9 rib area was evaluated by color reflectance and for myoglobin content. The roasts, procured from eighteen Duroc or Hampshire hogs, were classified subjectively into three color groups.

Color reflectance measurements on raw muscle indicated that as the subjective color classification increased from slightly pale (2) to slightly dark (4) the color was more dull and more purple. The color differences found by the Color Eye Colorimeter in the raw muscle were associated with the myoglobin content of the raw muscle (r = 0.791, P < 0.01).

Approximately 7 to 15 percent of the myoglobin remained after heating muscle to 155°F and essentially no myoglobin remained after heating muscle to 170°F. The sensory panel distinguished a difference in color between muscle heated to 155°F and 170°F as demonstrated by triangle tests. The panelists preferred the color of the muscle heated to 170°F. The color reflectance measurements did not distinguish a difference between muscle heated to 155°F and that heated to 170°F.