Originally Posted by bigabyte
I see this has turned into just a safety discussion, but I'm still not quite sold on the tenderness thing. It should be more tender at both lower temps and higher temps than at 145. 145 is right in the middle of the tough meat temps. It may be tender in the sense that you can chew it, but among all temps of doneness, that should be less tender than temps lower, and temps in the 180+ range.
This is and isn't true….Cuts that are high in connective tissue, such as legs/thighs in chicken and brisket/short ribs/shoulder in beef, have completely different cooking profiles than cuts that are very low in connective tissue, such as breast in chicken, and tenderloin/strip steak/rib eye in beef. At lower temperatures, the cuts that are high in connective tissue will be relatively tough compared to cuts low in connective tissue. As the internal temperature rises, there will be a point were all of the cuts will become tough and overcooked. But when the cuts that are high in connective tissue reach optimum internal temperatures for breaking down connective tissue, they will become tender again. Cuts of meat low in connective tissue will never become tender again. Chicken breast, Ribe Eye, etc.. will never become tender again at higher temperatures because there is not enough connective tissue to break down and turn into gelatin.