After knowing different type of muscle fiber, you may ask the question, what else does those meats contain? The first one I would like to tell you is so called connective tissue. For the connective tissue, it's function is responsible to hold all the muscles together. Actually, it can able to organize and coordinate the actions. For those muscle, which require more force, or more energy. Normally, it contain more connective tissues, so that it can able to hold more muscle, so that it able to do much harder work. So, that's why the connective tissue, normally, it is tough, and very strong. For connective tissue in most so-called [INAUDIBLE] land animal is actually relatively stronger. As you recall for the fish muscle, basically, it's only contain less amount of connective tissues because it's mostly don't required to work quite often. But, however, for those animal who live on the land, basically, they require the muscle function quite often. And then, eventually, the connective [INAUDIBLE] tissue in those lands animal is relatively stronger and tough. But however, as those animal getting old, the connective tissue is relatively tougher. So you may wonder what's inside the connective tissue. In fact it contains three type of tissues. The first one is so-called Collagens, second one is the Reticulin, and the third one is so-called Elastin. I will focus more in the Collagen, because Collagen constitutes The higher percentage in the connective tissues and especially for collagen. You may have experience that is when we try to heat it for certain temperature, the collagen is become softer. The main reason is for the structure of collagen. In fact, it contains three strands of amino acids. When it is being heated to a certain temperature, these three strands of amino acids start to unwind. Eventually, it becomes so-called gelatin, which has much softer textures as compared to collagen. To give you some idea is collagen, in most of the animals before it was born, once it's born basically the amount of collagen is more or less constant. It won't actually change too much. So that will explain why when those animals, when they are young. Once you hit it, basically, although it contains certain amounts of collagen, you still can able to change to gelatin. We still can give you some soft textures. But, however, as I mentioned, if that particular animal or the muscle is coming from the animal which is really old, those collagen, as times goes by, it becomes coalescing to each other. Even though, you try to heat it for high temperature, it won't break down any more, because it contains more elastin. So that explain why, for some old animals' muscle, even though sometime you heat it for a long period of time, it won't give you a tender structure. So, that's why collagen, in fact, it play a really important role in the meat textures. And for collagen to gelatin, as I explained to you a bit earlier, when you heat it to about 60 degrees the three strands of amino acids start to unwind. And then it converts to become gelatin. So this explain why, when or though your muscle contains lot of, so called conductive tissue, even though once you hit it at 60 degree for a longer period of time, it becomes so in structure. How about collagen in fish. As you all in know, in fish, it connect, it contain much less connective tissue. But for fish, if we look at the top part and also the tail, so you might know that most of the propelling force is actually, come from the tail of the fish. So you can actually immediately tell the tail of the fish, those muscle actually contain more connective tissue because it actually have to use quite often. But however, for those muscle in front of the fish, they hardly move, so that they contain much less collagen. So that's why, if, if the tail of the fish contain more so-called collagen or the connective tissue, basically, when you try to heat it to a certain temperature, eventually, the tail is give you more succulent texture compared to those muscle in the middle of the fish. So, gelatin and the fat in fat is just contribute the impression of the juiciness, moistureness of the fish's texture. So if, to a certain extent, if your muscle doesn't contains too much connective tissue, it actually give you a feeling of dried meat, normally, more or less in the middle of the fish muscle. But, however, for the tail, it actually contain more connective tissues. At a high temperature, it can able to connect to gelatin. It gives you a much more juicy texture afterwards. The next I'm going to tell you is the fat. Fat in fact we call a special form of connective tissue. And why do muscles normally contain fat? As you all know that this kind of fill actually was used by the so-called slow stitch muscle. And very importantly, fat is a source of energy. You can able to store normally under the skin. Not only under skin, sometime. To serve as a cushion, but it also being stored in the layer of the connective tissues. That is when the connective tissue try to hold the muscle fiber together there is always some fat, actually serves as a buffer as a cushion. So as I mentioned here, it can store under the skin, under the body cavity as a cushion. And it also lies in between the connective tissues, and separate all the muscle bundles together. And the role of fat especially in cooking. People think that fat actually is the component actually providing the flavor. And more importantly as a lubricant. It make the meat don't have a really dry and tough texture. And it always soften the meat when we eat it. So you're looking at these two pictures, what we can see on my right-hand side. Is a kind of rather lean structure whereas in this side what you can see is, you can see the fat is more or less evenly distributed among the meat, the, the muscle. Basically, it correspond to a more even kind of distribution. We use a term to describe it so-called marbling in the meat. So marbling means the pattern of the white spottage that goes, or actually distributed around the meat. If we have a really even structure, this is so-called the best, better quality. Whereas, if we don't find any so-called fat. This build in the meat, this will cause one to a relatively low-grade kind of steak. So, as I mention, the role of fat in the meat cooking is actually, it make the. the whole steak become more [INAUDIBLE] have more flavor and more tender and more suluent/g. And the fat is fish, it actually wear this. Some fish actually contain much less fat just like cod fish. Whereas other fish, it actually, like salmon, is contain a much higher content of fat. And primarily the fat actually store under the skin, or, in terms of between all the connective tissue, that it actually separate the so called myotomes. And if this actually contributes so-called both gelatin and fat. Both actually contribute to the juiciness of the meat when we prepared it or when we cooked it. The final component I would like to tell you is the role of the water. So, you may wonder, what is the role of water in the meat. Also, similar to the fat and also the connective tissue like gelatin it actually determines the texture and also to certain extent it correspond to taste. Most of water as you still remember, water is the major component inside the meat. Some meat actually contain over 70% [INAUDIBLE] water. So where is those water? Most of the time it's being trapped inside the protein of the meat. And it like, more less, it is locked inside the meat fiber. But, however, imagine when the protein, so called denatured. Denatured, I'm going to mention this term later in this course. The meaning of denature, what I would like to tell you here is just like it change to another form. So, if the protein, that the nature. The, the, the property of these proteins, once changed, it made it to the escape of the water coming out from the protein. Now, one questions, I guess some of you may experience is, why frozen meat always seems to be drier than the fresh one. The main reason is, the frozen meat, once it's been frozen, those trapped water may start to flow out from the thaw. And then, eventually, this phenomenon is so-called the free the bond water when they are defrost. That's why in those frozen meats, when they undergo thawing, those meats, once you cooked it, it appears to be much dryer compared to a fresh meat. Some people, once they defrozen some meat, they try to refreeze it afterwards, but in here I would say I try not to recommend you to do it. You know why? It's because when you try to frozen the meat the water inside the meat muscle, they start to crystalize. They become ice crystal. And the ice crystal is really sharp because they're solid they start to rupture the cell wall. Aand then, eventually, when you try to do the defrosting those trapped water will start to run out from the meat muscle. And then, it result to a kind of letting juice to escape out for meat's muscle become to a dry meat. And you may wonder why the water can able to rupture the protein molecule. So here is the water molecule H, which contain two hydrogen and one oxygen. In fact this molecule is extremely beautiful. It can actually organize itself to a really really regular structure. But before it goes to solid, it actually random, just like this structure. Water for it crystallize, become a ice basically, it just randomly arrange by themselves. But, however, when we try to lower the temperature. The water molecules start to crystallize, but how it can able to become a solid is because those water molecule, they become arranged really organized by themselves. This kind of rearrangement of the water molecule. Make the volume of the water molecule become larger. This explains why sometimes you might have an experience, that is you have a can of Coca Cola for example. If you put it in the freezer, if you don't, just you forgot you put a can of soft drink in the freezer, after two hours, what will happen? The whole can of the soft drink will burst itself. Why? It's because, as I just mentioned, the water molecule inside of soft drink is start to reorganize the volume. In fact, it's much bigger. Than the irregular form. It actually expand. The, the, the expose of this kind of, the expansion of this kind of water molecule actually, not only can able to burst, or soft can. But what you can imagine, you can burst. Protein molecules as well. So that's why when the meat actually, when we try to frozen it in fact the water molecule inside the meat muscle becomes crystallized it actually expands. In fact, to a certain extent this type of frozen meat, in fact, some of cell wall has been ruptured. And then, if you cooked it, you need to defrost it. And once you defrost it and the water, being at, or, or beginning, is being found in the protein. Start to running out and then eventually it reduced the water-holding capacity of the meat, and then it will result to a dry meat of those frozen meat compared to a fresh meat.
