<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Neanderthals had no problem with the plateau in meat, it was done when it was done or the fire went out, only modern man has that problem, I bet if you threw away the thermometer you will stop having plateau nightmares and your brain can rest; and that is my opinion but what do I know I’m not a scientist nor did I stay at Holiday Inn Express. </div></BLOCKQUOTE>
Albert, its not a problem, its a natural phenomenon. And as someone who has a mind for it, I like to try to come to a rational explanation for things. I've found that in my cooking, when I know the hows and whys, my ability to execute increases.
For instance, if the stall is directly related to evaporation, then it has implications on common techniques like foiling and mopping.
I appreciate the fact that some people enjoy the mysteries in life and prefer to let them be, but this thread was started as a technical discussion so lets treat it as such.
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> I didn't get through it. That's the consensus? I wouldn't buy that at all. It makes more sense to me that is a product of the much more rapid conversion at these temps (it's slower at lower temps). </div></BLOCKQUOTE>
I'm ever so happy you're still watching this thread. I considered pm'ing you on this one due to the gravity of the situation.
let me provide you with the cliff notes:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> We have done studies of meat in a differential scanning calorimeter (DSC). This is a device that looks for "stalls" as you heat things. It puts constant heat in, then watches how the temperture increases.
The most dramatic sort of stall is a phase change (ice melting, water boiling) but a DSC is made to have great precision in how it looks for ANY difference in heat versus temperature.
When you have a chemical reaction - like collagen converting into gelatin - it will show up with a DSC.
We have measured this transition and it is real, as is fat melting. Both contribute. However, neither one of them is big enough to really account for the "stall" observed by BBQers.
I think that a better explanation is wet bulb temperature. Basically, if you have a wet thermometer, it reads a lower temp than a dry one, due to evaporation (unless relative humidity is 100%).
Food mostly cooks at wet bulb temperature - until the outside is totally dry. I suspect that is that is the origin of the stall. </div></BLOCKQUOTE>
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Pure fat (i.e. rendered lard or suet) does have a relatively low melting point. It is not a sharp number because it is a mixture of different fats as pointed out in other posts.
When we talk about melting fat during cooking, we really mean rendering, which is largely about converting the collagen in the fatty tissue. Raw fat as it occurs in piece of pork or beef is NOT pure fat - it has lots of connective tissue in it, which is mostly collagen. So rendering fat out of a piece of meats is about both melting the fat, and breaking down the collagen. This is all pretty obvious if you try to render a piece of beef or pork fat - it takes a long time and a lot of heat. Compare that to melting some (already rendered) lard or suet.
The conversion of collagen into gelatin occurs across a wide range of temperatures, at a rate that increases exponentialyl with temperature. That is why we must cook 48 hours at 55C/130F to get tenderness that we might get in an hour at much higher temperature.
Anyway, it does take some heat to melt fat, and it does take some heat to convert gelatin. That will cause SOME stall, but I don't think that is large enough to be a real explanation.
My guess is that in a typical smoker cooking a big pork shoulder or brisket, the wet bulb temperature stays below 74C until such time as the crust of the meat is very dry, at which point dry bulb is more important. This is, of course, discussed at length in my book. This seems like a much better explanation to me. </div></BLOCKQUOTE>
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Heat gets into food from the surface. If the surface is wet, it will be at the wet bulb temperature. This depends on two things - the food staying wet near the surface, and also the relative humidity in the air around the food. If the humidity is 100%, as it is inside a SV bag then wet bulb = dry bulb. If the food is underwater, then there is no air to worry about and the temperature is again the same.
The surface is wet because there is water in the meat, but over time the surface layers dry out. This tends to raise the temperature until with a very dry crust on the meat very little evaporation will occur and the temperature will be at the dry bulb temperature.
The reason this affects the interior temperature is that the interior can't be any hotter than the surface. So if the surface is stuck at say 74C, then the interior can't get any hotter. As the surface dries out, the surface temperature rises, and sometime later the core temperature will too.
As Pedro points out this would not happen inside a SV bag (or in a combi oven or CVAP oven in low temperature steam mode.) Yes we have done the experiment (sort of) - we have recorded temperature in meat cooked SV or in combi for long intervals and we do not see a stall.
I say sort of because if you really wanted to check this out you would need to take two identical pieces of meat (say brisket), treat them indentically (dry rub and so forth) and then cook on in a smoker. We haven't cooked a whole brisket side by side. We did smaller pieces of meat, and we didn't do perfect comparisons. So a skeptic could still.
Most smokers / BBQs have no humidity control, and people don't know what wet bulb temperature is. We show in my book to rig up a wet bulb thermometer. We think that is how you should control your BBQ, and once you do that we think that reports of the "stall" will disappear.
I have several smokers and we have wet bulb temperature in them and you don't see a stall.
We have also done experiments using a convection oven, or a very fancy smoker, where you can show the wet bulb effect easily. Take a convection oven (or combi oven in convection mode), set the temperature to say 60C/140F and put meat in, it plateaus at the wet bulb temperature.
Finally, if you put meat in a DSC you can see a bit of a stall due to the various chemical changes that are happening but it is NOT a single fixed plateau, nor is the total amount of heat big enough to cause the reported hours-long "stall" that BBQers see.
Conversion of collagen into gelatin is complicated it does NOT occur at a single temperature - it is a reaction that occurs at an increasing rate over a range of temperatures, all the down to just above the animal's original body temperature. It does not occur "at" a certain temperature. </div></BLOCKQUOTE>
these quotes on egullet were authored by
Dr. Nathan Myhrvold
