Why it is necessary to rest beef after cooking?
Most of you will have heard about "resting beef" once it has been cooked. However I am still surprised to find many people have not yet heard of this concept! It was a concept I didn't know about until I was 24. I used to cook the hell out of each steak, turn it numerous times and then whack it on palate and think "gosh, I'm not a huge fan of steakThen I was given a few tips and learnt the reason as to why these tips worked. I will attempt to explain them in a way that does not bamboozle too much.
First and most simply - When beef is removed from the heat source it will continue to cook while the internal temperature drops, so really you need to remove your beef before it is cooked to your desired "doneness."
Secondly (with a bit more complexity), Meat is a muscle and made up of intertwined protein fibres. When you start to cook beef the proteins contract and change shape, shrinking in size. There is a change at a cellular level and the water molecules (the juiciness) that previously bonded to the amino acids are no longer attracted & the water is repelled. Also the steak shrinks and the internal pressure builds up. This is where you will see beads of moisture on the top of your steak. This moisture seeping out is what is necessary for that "juicy" steak, so it is important to never cut your steak to test for doneness, or cut too early as you will lose this moisture.
When you rest the meat, the temperature drops, the proteins stop changing and the water molecules have time to find new proteins to rebind too. The internal pressure will drop as the protein fibres widen and relax and this lets the water be redistributed.
So! The best way to rest a steak is on a warmed plate, with foil tented over it (not completely sealed as this may cause the steak to stew). I generally rest for at least half to to full cooking time again. If there isn't a warm spot to rest it I put in into a very low oven. With roast beef (&lamb) I like to give it 20 minutes and again I cover in foil and often a tea towel as well to keep warmth.