My Wife got me one quite a while ago, have been trying my best at lower cost beef, I just cant get it right, I hour at 140 just returns me a tough piece of meat, same with differant times and temps, can I really expect it to tenderize meat ? I dont buy the cheapest, just not prime.
The answer is absolutely yes.
Several factors come into play, such as thickness and cut, but basically after about an hour the meat is fully cooked. From one hour to about 4 hours all the connective tissues start to break down and tenderize. After 4 hours, the protein fibers actually start to break down and the meat will sort of take on a mushy consistency.
In short, you can take a cheaper cut of meat and cook it anywhere between 1.5 and 3.5 hours and you'd never know it wasn't prime.
One of my favorite things about the sous vide is that it allows you to have a perfectly cooked entree as soon as the rest of your meal is ready. Doesn't matter if the baked potato is taking too long, or the wife burned the risotto and you had to start over. As soon as the rest of the meal is pulling together, you sear the meat to your satisfaction and everything is hot and ready at the same time.