Mozzarella melts, feta crumbles and Parmesan puffs up in salty clouds when grated. But so far as I know, only one common cheese ― halloumi ― squeaks. I’d always thought the high-pitched sound I hear when biting into the Cypriot classic was down to its slightly rubbery texture.Then again, the noise doesn’t sound when I’m chowing down on similarly bouncy foods like tofu or even string cheese and Edam (although it does happen when I eat green beans).So what’s going on, and why isn’t it consistent across the springy cheese multiverse?It’s to do with how proteins in the cheese are maintainedAccording to New Scientist, it has to do with how the protein casein interacts with the enamel of your teeth. Unlike other cheeses, halloumi isn’t made with any starter cultures. That gives it a high pH, which helps to keep a protein called casein, which is present in cheese, more intact than usual. So while some Edam might feel as rubbery as halloumi, its casein proteins aren’t as dense and bouncy, thanks to its lower pH levels. That means it creates less friction.