The Rest step: When needed and Why
Many of the barbecue’s contact points with traditional cuisine are still characterized by that mystic mystery shadow, which only the wacky and indefinite world that generates the cult of 3-star chefs knows how to create. It is an impenetrable context capable of generating absolute dogmas, which in many cases reduce theirself to the creation of commonplace such as “not salting food before cooking”. One thing that makes me happy about the world of barbecue is its willingness to always add a “because” by the side of a rule.
Right in this light it is useful to deepen one of the many tips that are generally associated with the barbecue, that of adding a resting phase, post-cooking to our preparations. The rest takes on particular importance, though for different reasons, mainly in two distinct contexts: in the purest barbecue and in traditional grilling, in particular the steaks.
The Rest in american barbecue
It assumes a determining role in relation to another well-known element in the branch: the collagen. It is a protein compound mostly contained in the poorest cuts and in parts of waste such as bones, joints or subcutaneous tissues. 
The amino acids model them through triple helix structures that tend to connect with each other with a different intensity depending on the age, life or genetics of the animal, creating the famous “net” to which we tend to bring the famous role of Bite stiffening to collagen in case of inadequate cooking. In a humid, low and constant temperature, slowly passino the 60° C the elices begin to shrink and roll, weakening the fiber-containing net.
Now, have you ever tried to make broth, let it rest in the fridge and find a solid jelly the following morning? This is because after the collagen degradation process has been completed, a subsequent lowering of the temperature will lead to a tendency to reconstruct the bonds. The process, however, is irreversible and will create a highly unstable structure that will tend to irretize the water molecules that in the meantime have released during cooking, the famous gelatine, which under 35° C will assume a solid consistency, unless rehearsing with heating. An important factor in this process is the time it takes: the construction of these bonds is relatively slow, so the lower the temperature will decrease, the more bonds will form and the thicker the network that forces the water molecules.
How can all of this help us in the barbecue? Let’s suppose to cook in Low & Slow a pork shoulder to get the fantastic Pulled Pork. When the right temperature is exceeded, all collagen propellers will be degraded, but if we immediatly pull it, it will tend to dehydrate very quickly. Free juices will tend to evaporate quickly leaving a pulled pork dry and uninviting. It is only the phase of rest that it will create the conditions for gelatin generation, which, in addition to liquid costraint, will act as a lubricant between the fibers, attributing to the bite the incredibly delightfulness that makes the pulled pork just one of the most famous and appreciated dish of America’s BBQ.
The Rest in grilling
This is in fact a less scientific and more empirical approach, which makes the subject very debated and subject to various debunking attempts by many sites. For what is my experience, I find myself very in line with the results obtained from sites like Serious Eat, where it is shown how the fibers behave like liquid containers, whose ends contract if they are stressed by heat, forcing the juices in the farthest part of the surface. At this time, the meat behaves like a bottle of soda that has been shaken: the content under excessive pressure will tend to explode outward if the bottle is opened. The steak then if cut immediately after being taken out of the grid, it will lose the excessively concentrated juices in the central part. A phase of rest will tend to loosen the contraction and restore the equilibrium. For complete information, there are those who argue that the reason is actually due to a thickening of the resting juices. However, for our purposes, the result does not change. Some argue that this phenomenon is simply due to a change in density of the juice inside the steak and not to changes in concentration. From this point of view I use my usual approach of a passionate agnostic: I limit myself to hypotheses supported by sources the most authoritative on fields where it is assumed they have more title than me to express and cross them with my empirical experience to get my personal conviction out of it. In this specific case I am much more inclined to validate Serious Eat’s thesis. One of the criteria of rest on grilling that I think works best is to insert a probe into the steak while resting, wait for the carry over to cease and the temperature to drop. As soon as the degree is lowering, the steak will be ready to be sliced and served. So it’s logical that this time is a function of the different mass. If it were a simple change in density, how much could the lowering of a degree affect? In all probability nothing. Instead, following this method there is a tangible and evident change in the loss of juices.
The only thing I have to argue with is the tendency of Serious Eat to give the timing that, depending on me, depends on a case by case, depending on the thickness, the mass and all the other factors that usually affect the cooking of a steak. The tests show how in the rest, the surface temperature of the steak will be the first to drop, creating the conditions for restoring the spread of the juices and only then will the internal temperature drop. My approach is personally to never go beyond this stage. Ideally, you should leave an inserted probe and cut the steak as soon as we verify that the heart temperature has a bounce..
Have you ever noticed how important the rest period is?
