When cooked properly, tough cuts of meat like beef shank and pork shoulder transform into fork-tender meat swimming in a rich braising sauce. How does this magic happen — and how long does it take to get there? America's Test Kitchen ran some tests that make it clear why tough meat tastes best when its braising liquid is full of gelatin.
When you cook a tough cut of meat, the hard-to-chew collagen in the flesh breaks down into gelatin, which is what gives the finished braising sauce its silky richness. The more gelatin in the sauce, the more tender the meat. To demonstrate how gelatinous the braising sauce is at each stage in the cooking process, the cooks at America's Test Kitchen chilled a sample of the sauce after one, two and three hours of cooking.

Not surprisingly, the sauce after one hour was loose and mushy, while the three-hour sauce stood up as firmly as a slice of Jell-O on the plate. It's a visual reminder of why tough cuts of meat need so long to cook, and why you shouldn't waste a single drop of their delicious braising liquid.
→ Read more: We Prove It: Cook Tough Cuts Beyond Well-Done at America's Test Kitchen
Related: What Can I Do With Leftover Braising Liquid?
(Image: Faith Durand; America's Test Kitchen)
Elizabeth Apron fro...

...and with a 48-hour sous-vide at 141F, you can keep all that delicious liquid inside the muscle and keep the pinkness of medium rare... just make sure you have your sous vide vessel insulated from the quartz countertop it's on, or expansion can crack it (voice of experience)
I've had a hard time using up braising liquids in the past because there were too many unique seasonings for the original meat recipe. Because it wasn't a simple combination, it wasn't as versatile. So, when I did a pork roast in the slow cooker this week, I just used onion, garlic, salt, and pepper. Then, when I decided to make pumpkin soup a couple of days later, the pork braising liquid was perfect in place of the chicken broth in that the recipe. And today, I used the rest of the braising liquid from my pork roast in a chili recipe. Again, because it's more of a neutral seasoned meat flavor, the braising liquid more easily lent itself to future uses. And the pork roast was delicious, too. After hours in the slow cooker, it was tender and ready to be served as pulled pork, which I seasoned with a good barbecue sauce after I drained most of the braising liquid...This is probably a really elementary tip to share, but it felt like a mini breakthrough for me. And I'm planning to do something similar the next time I make roast beef.
You know, I like using a tomato/pepper sauce to braise my meat in. The extra I save for pasta and it goes great on polenta too (with or without the meat).
aaaaaah, beef shank. i'm so glad i was recently introduced to it. what with tongue, tripe, shank, and tendon, the cow is becoming as magical as the pig.