The Effects of End Point and Oven Temperatures on Histological Characteristics of Beef Longissimus Dorsi

(From the Summary): The effects of heating beef rib roasts to end points of 140, 158, and 170°F at 225 and 325°F on histological characteristics of longissimus dorsi were investigated.

Muscle fiber diameter was greater for raw than for cooked tissue. Generally, fiber diameter decreased at both oven temperatures as end points increased from 140 to 158°F. Raw and/or cooked samples contained straight, accordion pleated, and waved fibers. The predominance of straight fibers tended to decrease as wavy and accordion pleated fibers increased. End point and oven temperatures appeared to be unrelated to the occurrence of waves and/or accordion pleating in muscle fibers.

Fibrous collagenous connective tissue was present in all raw samples, but with increasing end point and oven temperatures, there was a slow change from the banded to granulated form. A moderate amount of fat with medium to large size cells was present in endomysial and perimysial collagenous connective tissue. As end point and oven temperatures increased, the melted fat dispersed from the fat cells into the banded and then into the granulated perimysial and endomysial collagenous connective tissue.