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pressure cooking school  Welcome to Pressure Cooking School!
 This article is part of Lesson 6: Marvelous Meats

When I pressure cooked my first roast, I was so excited. I quickly opened the pressure cooker and I looked inside and it was beautiful and moist and it smelled really good. I couldn’t wait for my family to see it. So I put it on the serving platter, called them up to dinner, and…  I couldn’t recognize what was on that serving platter! The roast had shrunk down to this brown, tasteless, hard thing that did not even resemble a roast, anymore.

The roast misadventure set me on a mission to find out why this would happen. So I searched and searched, and I found this little bit of physics knowledge about how the higher the temperature of a liquid is, the faster it evaporates! Let me explain that a little bit and how I applied it to pressure cooking to reveal the fourth secret of marvelous pressure cooker meat.

Why Pressure Cooked Meat Dries

How A Slow Pressure Cooker Open Keeps Meat from Being Tough

Cold – Let’s start with a cold piece of meat out of the refrigerator. It does not have any significant evaporation because it is not being cooked.

Conventional Cooking -Then, let’s look at a piece of meat from the oven or a pan. When it’s cooling it will have some evaporation but it won’t be a significant amount.

Slow Release – A piece of meat that is pressure cooked, but opened with a slow pressure release, like my recommended Natural Pressure Release, will evaporate slightly more moisture than the one that was conventionally cooked – but,  not a lot.

Fast Release – And, finally, let’s see what happens to a pressure cooker roast which was pulled out of the pressure cooker as fast as possible using quickest pressure release, such as Normal pressure release. The meat is really, really hot and a majority of the moisture begins evaporating away super quickly.

And that’s why for most recipes I recommend using the Natural pressure release. It gives the meat’s juices enough time to lower their temperature slowing the evaporation.

Taking Advantage of Accelerated Evaporation

On the flip side, there’s a way to take advantage of this accelerated evaporation and use it for good. It won’t work for steamed meats, and it won’t work for braised meats, but it WILL work for boiling stew-type recipes. That’ where the meat is covered in cooking liquid and the goal is to reduce it to concentrate the flavor. For these recipes, it’s OK to use a faster pressure release. The liquid insulates the meat and keeps it from losing moisture. While the cooking liquid evaporates to concentrate the remaining flavor.

So, that’s enough talking and illustrating, now. Let’s try it out and put everything we’ve learned to work.

CONTINUE…


pressure cooking schoolCONTINUE Lesson 6: Marvelous Meats

How a FAST pressure release can RUIN meat When it's OK to use a FAST Pressure Release

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11 Comments

  1. I still come across meat recipes recommending the fast release method, despite the meat not being immersed under liquid. Not sure if whole chickens (or even chicken breast pieces) would overcook from the natural release method? Confusing! Please clear this up. Thanks.

    1. Well, I can’t speak for others, but the “exception” to Natural Release for meats is something I came up with after research and testing. Previously, I thought ALL meats should ALWAYS be opened with Natural Release. But when I realized how accelerated evaporation can suck the life out of a piece of meat I started applying some of what I learned to reduce sauces (which I describe in the Hip Pressure Cooking cookbook – and have since seen used by the likes of Kenji at Serious Eats, etc.). For meats, I started to slowly introduce the exception on this website in a few recipes explaining why I was not using Natural Release. With this lesson, I can share my “latest thinking” on this subject all in one place – plus add animation to bring it all home. : )

      Sorry, I only partly answered your question.

      Ciao,

      L

      1. P.S. I read a few studies about meats cooking at high temperatures – check out the summary on chicken nutrition and moistness – that basically said that when there is a high-fat content it’s practically impossible to overcook meat. The fat has somehow helped retain the moisture at the highest, and particularly pressure cooking, temperatures. The researchers didn’t explain the mechanism behind it but it’s probably close to what myself and other ladies do when spreading fatty anti-aging creams to keep the moisture in our skin and create creating a barrier from the elements.
        https://www.hippressurecooking.com/pressure-cooker-chicken-nutrition/

        P.P.S. since you’re in the U.K. you should know how popular boneless, skinless, chicken breasts are in the U.S. and since they have NO fat a recipe that is not carefully thought-out in cooking time and opening method is a guarantee for disappointment.

  2. But most moisture loss in meat is not caused by evaporation. It happens when the protein matrix in meat collapses while it’s cooking and forces liquid out. That’s almost completely dependent on the temperature to which the meat is cooked (think about how much drier well done steak is than rare or medium rare steak, or how water seeps out of overcooked scrambled eggs). It happens whether the meat is submerged in liquid or not.And as far as I’ve seen in numerous experiments, the method of pressure release doesn’t affect it.

    1. I know from practical experience that rapid pressure release will result in a tough dry piece of meat. A more gradual pressure release will result more pleasant tasting piece. for the same cut and cooking method.

      So let us examine what is going on…
      1. The recommendation is to pressure cook cheap cuts of meat – the ones that benefit from long slow conventional cooking. Not prime cuts better suited to rapid frying. What we are seeing is the rapid breakdown of collagen and gristle into gelatin. This gives the mouth feel of tender moist meat.

      2. In a pressure cooker you are cooking in a (relatively) high pressure and humidity environment. Even if the moisture is forced out of the meat cells, it has nowhere to go. With 100% Relative Humidity it cannot just evaporate from the surface, and the pressure is driving it back into the meat. If the meat cools under pressure, then as the fibres relax some of that moisture will absorb back into the meat. Contrast it to the situation where pressure is reduced rapidly and the lid is removed while the temperature is still above normal boiling point. Humidity and pressure will both fall dramatically, and the still hot meat will drive off the moisture still present BEFORE the fibres relax and can reabsorb some of the moisture. The collagen and fat present, both of which contribute to mouth feel, will also be driven out of the meat.

      Think back to your steak example. If you do not rest a steak, it will be drier and tougher than if you do allow it to rest. Though most of what is talked about in the mystique of “resting” is nonsense. Think of slow release as “resting” the meat.

      As for your scrambled egg example. I have cooked a lot of scrambled eggs over the years. Sometimes very badly. I have never seen the phenomenon you describe.

      1. Thanks for the information. I know that cuts of meat with lots of collagen and fat are the best choice for a pressure cooker; I’ve written two pressure cooker books (and two other cookbooks). I also know about collagen breakdown (my understanding is that other connective tissues such as elastin don’t break down nearly as fast — is that what you mean by “gristle’?). I disagree with your assertion that cooking under pressure drives moisture back into meat. If that were the case, why not cook your steak in a pressure cooker? It couldn’t lose much moisture, according to your hypothesis. As for the moisture in meat and quick release, see below.

        It’s my understanding (per Modernist Cuisine and other sources) that resting a steak helps make it seem juicier because as the juices cool off, they thicken, and coat the meat more thoroughly. They don’t really “reabsorb” into the meat tissue. I have never seen the parallel between that and natural release, since that liquid is still very near the boiling point.

        1. Hi Janet,
          You clearly have better cooking credentials than me. I am a home cook with zero cookbooks to my name. I do have an abiding interest in the how and why of things though. And I do have a Physics degree. Admittedly several decades old now.
          I am on a fixed (low) income these days so my experiments these days tend to be thought experiments.

          My apologies if I gave the impression that the pressure was driving the moisture back in. I do not think that. What is ( I think) happening is that the high pressure is raising the boiling point and the high humidity is lowering the evaporation to virtually zero. Between the two very little moisture will leave the meat completely, though it will certainly leave the cells as the muscle fibres contract under heat, and probably will mostly leave the interior as the piece of meat shrinks.

          When the temperature drops, the muscle fibres will relax somewhat. Not completely as the change is structure is partly irreversible. and if the moisture is still around, some of it will be drawn back in to the interior. The moisture will still be around if the PC is still under pressure as the humidity remains high. It won’t be if the lid has been removed early, lowering both the pressure and humidity at a blow.

          Your experiments seem to directly contradict both Laura and my experience. I am wondering if it is because of the cuts of meat involved. You appear to have used steak sized cuts. I have noticed the drying out and toughening in roast sized pieces.

          I no longer pressure cook steak sized pieces. I Sous Vide them almost exclusively. And ensure that the temperatures remain low enough that the muscle contraction does not trigger. 50.5ºC for fish. 55ºC for most other meats*. 62ºC for chicken and mince products (e.g. Sausages)

          I do still pressure cook Corned Beef. I have found that is best if I not only let it reduce pressure naturally, but let it sit undisturbed for about an hour after I turn the heat off.

          * a fraught term. For me “meat” means any muscle fibre from any animal – including fish. Any other definition seems to be driven by religious rather than scientific reasoning. I know people who insist that if it is not from a cow it is not meat. There is meat, lamb pork, fish etc. Even veal is not meat. I guess it makes being a vegetarian easy.. And abstinence on Friday is a doddle – They are Catholics.

    2. Janet,

      I’d like to find out more about the phenomena you describe. I’m specifically interested in learning more about the “collapse of protein matrix” you mentioned as I’ve only seen this term used for emulsification of liquids or for production of a meat extrusion (ie. pink slime) but not applied directly to meat for cooking. Just because I haven’t seen it, it doesn’t mean it doesn’t exist, so please share your references and citations so I can better understand what you are sharing here.

      I have not had the same experience as you, either – and this is after pressure cooking meats for almost 15 years. You also mentioned experiments that prove this. Are the experiments in published literature or your own? If they are from your own experience, it would be great if you could share what kind of meat was used, what the recipes were, what kind of pressure cookers this was tested in, and how you measured the state of the “meat protein matrix”.

      If there is a way to get great meat dishes even faster, I’m all for sharing your technique with my readers!

      Ciao,

      L

      1. Laura,
        I took Janet to be referring to the contraction of muscle fibres when heated above about 58ºC. See Modernist Cuisine for details. This certainly drives moisture out of the meat*. I had not seen the “collapse of protein” terminology before.

        *And goes a long way to explaining why I like my steak cooked to 55ºC by sous vide.

      2. Laura, I have also been pressure cooking meat for about 15 years. Aside from general experience, my particular experiments are these:

        1. First, I cut a pork tenderloin in half, seasoned and seared both halves. I cooked half in each of two electric pressure cookers at the same time. The first I set for 0 minutes on low pressure, and let the pressure release naturally (I believe that took 10-12 minutes). The second I set for 4 minutes on low pressure and quick-released the pressure. I timed the two cookers so that the tenderloin halves finished within a couple of minutes of each other. I took the temperature of each and they were virtually identical — about 145F. I let each rest for a few minutes, then sliced and served myself and 3 guests, putting some of each tenderloin half on each plate. No one could tell any difference. I’ve also done the same with chicken breast, with the same results.

        2. Admittedly, that depended on the subjective judgments of my guests, so I devised a second set of experiments to measure only the moisture loss of meat under natural and quick release. (I did all of this set in my Instant Pot Ultra.) First, I measured the amount of liquid lost in the pressure cooker just using water to get a baseline. I added 500 grams of water and set the pressure cooker for 10 minutes on high pressure, with complete natural release of pressure, which took 20 minutes. The pressure cooker lost 20 grams of water (that is, I ended up with 480 grams, give or take a few grams that may have been clinging to the pot). So it lost about 4 percent of the water. I then did the same thing (500 grams of water, 10 minutes high pressure), but with quick release. In that case, the pressure cooker lost 40 grams of water, so twice as much, but still not much compared with the staring volume.

        Part two was cooking meat. I chose two pieces of pork shoulder that were similar in appearance (that is, they had very little external fat and looked to have about the same amount internally) and were taken from the same shoulder piece. I cooked them plain so salt wouldn’t interfere with the transfer of liquid, over 500 grams of water on a trivet. This time I cooked them for 30 minutes. With the first, I let the pressure release naturally; with the second I quick released the pressure.

        In the first cooking session (with natural release), I started with 440 grams of meat and ended up with 264 grams, or 60% of the starting weight. I ended up with 625 grams of liquid, or 25% more than the starting weight. After weighing the meat and liquid, I took the temperature of the meat in a few places and got readings of 190F to 194F.

        In the second (with quick release) I started with 425 grams of meat and ended up with 272 grams, or about 64% of the starting weight. I ended up with 590 grams of liquid. To compensate for the extra 20 grams I presumably lost due to quick release, I added that for a total of 610 grams, or 22% more than the starting weight. The ending temperature of the meat was comparable to the first batch.

        So, here’s my conclusion. I assume that the change in weight after cooking is due to liquid leaving the meat, and to fat rendering out. Quick release DID NOT cause more liquid to leave the meat (as a percentage of starting weight); in fact, slightly less did. Further, assuming that the increase in liquid in the pot was due to liquid leaving the meat and fat rendering out, again, there was more liquid after natural release than quick release. Obviously I want to repeat these experiments, but my preliminary conclusion is clear — quick release on its own does not dry out meat.

        (You will notice that I didn’t talk about toughness, since that’s difficult if not impossible to measure by objective standards. I will say that the day after cooking when I shredded the meat, I found it impossible to tell which piece was from which batch. But that’s subjective.)

        I know that many people (you and Greg included) claim that in their experience, quick release dries out meat. Obviously I can’t account for your personal experience, but I haven’t read of anyone doing similar experiments and getting vastly different results. Until I do (or if I get vastly different results when I repeat my experiments), I’m standing by my statement.

        (I got the language and information about protein matrices from the book “Ingredient” by Ali Bouzari, a chef with a PhD in food biochemistry. He actually uses the term “protein web”, so I guess I misspoke slightly.)

      3. @Laura,
        This discussion seems to be quite worthwhile to me, but it appears to be getting away from the point of the page.

        Perhaps move it to the forums. And then update this page if it proves necessary.

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