Originally Posted by bigabyte
All things said, however, I'm intrigued by the idea that a longer hold at a 145 temp may cause the meat to become tender. I'm not discounting it. I'm just saying I am skeptical is all. The thing I am most skeptical of is whether a simple 10 minute hold is enough to break it down to being tender. It's long enough to kill bacteria, obviously, but it's another thing entirely to say that is the time needed to make a piece of meat that should be tougher than normal at that temp breaks down to being tender in just 10 minutes. Thus why I question it.
I've never been one to blindly follow. I've also always been quite open to the idea of being wrong, so long as someone can back it up. Usually folks can't back it up and it has to be "tried". I'm not all that keen about the idea of trying it, but after all of the safety discussions my primary concerns have been alleviated.
We also need to know for sure that Harry holds the chicken at 145 as opposed to simly wrapping it at 145 and continuing to cook it. The meat may still be rising in temp, changing things entirely. Thus some clarification is needed.
It's more tender than at 165 because it hasn't toughened up as much and there is less moisture loss. Just like a rib-eye will be more tender at 130 than 160. The ten minute hold is simply for safety, not to tenderize. The muscle fibers will not have constricted as much as at 160. It will be juicier and more tender. I have done multiple experiments in a sous-vide machine at 140, 150, 160, and 170 degrees with chicken breast. It consistently will be tougher and less moist as the temperature is raised. The temperatures are not high enough to break down enough connective tissue in the breast to tenderize.