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- When you think about cultures that eat cheese, and cultures that eat tofu, they don't seem to overlap so much. But are these two foods really worlds apart? Hi, I'm Julie. Welcome to Hungry for Science. Here in the U.S, it's pretty common to find a carton of milk in people's refrigerators. In East Asia, it's much more common to find soy milk because people tend to become lactose intolerant as they get into adulthood. Soy milk is used as an alternative to dairy milk around the world, both because of the lactose issue, but also for vegans who don't wanna consume animal products. Now, cheese is a concentrated form of milk. It's what happens when you remove water from milk. And the way cheese is made, is by clumping the proteins that are in milk together. It's a process called coagulation. The proteins coagulate, and the water gets filtered away, and you end up with cheese. So today we're gonna see what happens when you coagulate the proteins in soy milk. So I have a pot of cow's milk and a pot of soy milk, and I've heated both to just below their boiling points. And I'm gonna add something to help their proteins coagulate. Acids are a great protein coagulator. And I squeezed some lemons to make some lemon juice, and I'm gonna add some lemon juice to each pot to see what happens. So first, I'm gonna slowly add lemon juice to my soy milk, gently stir it in. And I have another container here. I'm gonna add to my heated cow's milk. And normally I'd let these sit for a few minutes, but really it doesn't take long. Even after a few seconds, you can see that proteins are starting to clump together. They're getting into these little chunky balls of protein masses, and we call these clumps curds. So these curds are separated in the cow's milk, and also in the soy milk. You also see similar-looking clumps as the proteins bind together and separate out from the liquid. So we're gonna go ahead and strain the clumps out of the liquid and see what we get. So first with the cow's milk. And I'm gonna let that sit for just a minute while the liquid drains out. The liquid is referred to as whey, and these clumps are the curds. So these are the curds and whey of milk. And the same thing with the soy milk. And I'm also gonna let these drain. So if we take a closer look at the dairy milk, the whey's draining away, and lo and behold, we have fresh cheese. Some people press this and call it Paneer. Others call it farmer's cheese. Kinda has the texture of ricotta, but it's a little different from ricotta because it was made from whole milk. So I would normally let this strain for a few minutes, and then use it just like I would any kind of fresh cheese. Now, in my soy milk case, it's still draining. And normally this whole thing would be filtered and put into a mold, as these curds become what we call tofu. So the coagulated proteins in soy milk get pressed together and drained, and you end up with tofu. So if you wanted to, you could just fold this up and press it down with a can of tomatoes or something to get all of the water out. I actually have some that I made yesterday and pressed of each kind. You can see the fresh cheese. I did not press it, actually. I just sieved it and put it in a container, but it still has that creamy, ricotta-like texture. And my tofu has firmed up just like tofu that I would buy in the store. It's not the nice rectangular shape because I just pressed it in my strainer. But when I break it up, you can see that it has the same texture of any tofu that I would buy. And the longer you press it, the more firmer it will be. Now, tofu traditionally is not coagulated with lemon juice. Folks use different kinds of salts, and depending on what you use, you'll get a slightly different texture. Some tofu's more silky. Some tofu's more cottony. But you can see that even though cheese and tofu might seem like they're worlds apart, they're really quite similar. They're both ways to extend the shelf life of different products; milk in the case of cheese, and soybeans in the case of soy milk. And both, thanks to science, are really easy to make at home.