If the last post in this series was about flavour, it makes sense that this one is all about texture. I talked about texture in a general sense in part 1, in terms of balancing a need to keep tender muscle fibres and breaking down connective tissue. In part 3 I’ll focus a lot more on that last part – how the bits holding your meat together fall apart and change your tough piece of pork shoulder into beautiful pulled pork that you can shred with a spoon and easily eat.
To briefly recap part 1, pieces of meat that had to do a lot of work for the animal in question tend to be tougher because they require a lot of connective tissue to hold together muscles and hold these muscles to the bones of the animal. They work hard and as a consequence are typically considered very tough cuts of meat. With the right cooking, however, they can become exceptionally tender and soft. We cook these cuts slowly, at lower temperatures and for a long time to get this texture, so think about pot roasts, stews and US-style BBQ.
As mentioned in part 1, the most common type of connective it collagen, which when cooked to a certain temperature for long enough denatures and breaks down into gelatin. Collagen is tough, hard and unpleasant to eat, whereas gelatin is soft, easy to eat and creates a beautiful texture. Gelatin is what you, as a cook, are after.
The process of turning collagen to gelatin begins at about 60ºc, when the collagen begins to shrink and squeeze out liquid. Meat cooked to around this temperature will suddenly start to release a lot of liquid as this process starts to happen. This is the point at which it starts to become drier and tougher: the moisture is being released and the protein fibres are denaturing, so you end up with hard bundles of muscle fibre with little liquid to lubricate them unless it’s a slightly fattier cut. In practical food terms, a rare steak is heated to about 60ºc, with well-done at about 75ºc – so you can see why a well-done steak can be very tough. Thinking back to that piece of pork shoulder, at this point it’s rock solid and largely inedible.
After a bit of time at 70ºc, the collagen cells start to dissolve into the gelatin that you’re after. The actual muscle fibres aren’t any weaker or more tender, but they become vastly more and more edible with every collagen cell that breaks down. It’s not because the protein strands themselves have changed – they’re still tough from the heating you’ve already done – but as they’re no longer held together by the connective tissue, you can easily separate the fibres. This is why you can ‘pull’ slow cooked meat: after the gelatin is gone there just isn’t anything to hold it together anymore, and the presence of the gelatin makes up for the moisture you’ve lost.
Simply heating a piece of meat to 70ºc however isn’t enough – otherwise that well-done steak would be tender and delicious. The hotter your meat gets, the faster the collagen dissolves and the more of it dissolves. If you haven’t broken down all the connective tissue, you won’t get that soft texture and you won’t be able to pull your meat apart. This is where the time element comes into play: you simply need to be patient and leave your meat alone until all of the collagen has broken down. Your pork shoulder may be soft in places, but you’ll find yourself left with a good few tough spots if you don’t allow it to cook for long enough.
Collagen dissolves very quickly at 90ºc, so by the time you get to this point your pork shoulder will be ready to shred and deliciously tender with tonnes of gelatin flowing around. So if you’ve got a probe thermometer, this is about the temperature you need to be aiming for. If you don’t, then you’ll be able to tell if it’s ready or not by the ease (of lack of) at which it pulls apart when gentle pressure is applied. Whilst this may seem straightforward, it’s worth bearing in mind that this can take a really long time. Professional BBQers talk about the temperature plateau – it’s quick and easy to get to 70ºc, but takes ages to get to 90ºc. This is due to the moisture release that I mentioned earlier as it slows down the heating process from the inside. Nothing you can do about this I’m afraid – patience is key.
Once cooled both fat and gelatin become more solid, so make sure you shred your meat before it gets too cold.
As before, reading list & references used in part 1.