Why does meat need to "rest"?

 So you have to wait a little longer before you start eating the amazing-toasted steak? Unfortunately, Yes. Here's why. In the photo — a steak that was cooked in a pan before roasting medium rare (temperature 51.7 C). After that, we immediately cut it in half and it literally flooded the cutting Board with juice. As a result, the steak lost in juiciness and taste. This could have been avoided if we had let him rest.  When the surface of the meat touches the hot pan / grill, the liquid from the outside goes to the center and it is oversaturated. Once we flip the meat, the same thing happens on the other side. So when you cut the steak immediately after roasting, most of the juice just flows out. During the rest, the liquid is evenly distributed back-from the center to the edges. Imagine that a steak is a big bunch of straws, each of which is filled with liquid (these are muscle fibers). During the preparation of the straws change their form, is compressed, the pressure increases. Most of them are compressed at the edges, less-in the center. Therefore, it is logical that all the liquid will be there. But the water is not compressed. If you have a two-liter bottle filled with liquid to the neck, it is almost impossible to add something else there without changing the volume. About the same thing happens inside the steak. Once the center is heated to 51.7 C, the muscle fibers contract, pushing out the fluid. Where does it go? Where it can — beyond the fibers to the surface of the steak. Let's give the theory a rest. So why does a straight-cut steak give off more juice than the one that's rested? It's all about the temperature. We already know that the width of muscle fibers depends on the temperature at which the meat was cooked, and from a certain moment the changes take an irreversible character. Meat cooked to 82.2 C, will not be able to accommodate as much liquid as raw. But once the meat has cooled slightly, the muscle fibers relax. In the photo-6 steaks of the same thickness, which we cooked at the same temperature of 51.7 C. After cooking every 2.5 minutes, we cut the steak and fixed the spilled juice. That's what happened.: - Without rest: the temperature of the outside of the meat is about 94 C. the Muscle fibers are tightly twisted and are not able to retain liquid. The temperature of the middle part is 51.7. Cutting the meat at this stage is like cutting a soda bottle. It certainly something will remain, but most will evolve. - After 5 minutes: the outside temperature dropped to 62. 8, and the center is still 51. 7. C. at this stage, the muscle fibers relax and become slightly wider. Under pressure, the liquid returns from the center to the edges. As a result, there is less juice on the plate. - After 10 minutes: the temperature of the outer part is about 52 C. the Uniform distribution of juices and surface tension leads to the fact that the liquid does not flow on the plate. The difference is clearly visible in the photo. But what if, while the meat was on the plate, the juice just evaporated and we had the same dry steak in front of us? To check this, use the scales and weigh the steaks before and after cooking. In the process of cooking the meat has lost about 13 % by weight. Cut immediately after cooking-another 9 %, while rested-only 2 % Big pieces of meat. The above rule works great with small steaks, but what about big pieces like pork loin or prime rib? The same principle, but the main difference is that you need much more time to rest. How to define it? With a thermometer. It is not so important what kind of roasting you have chosen for the meat, as soon as the temperature inside the piece dropped to 49 C, it can be cut and served. Your meat is 7% juicier)