By: Katie M. Palmer
Red jalapeños give rooster sauce its heat; they clock in at about 5,000 Scoville units, or around 300 parts per million of mouth-burning capsaicinoids. These molecules bind to a receptor, TRPV1, that shows up on the ends of nerves that lead to the trigeminal nerve, which conveys touch, temperature, and pain.
The sulfurbased molecules that give garlic its stink activate another trigeminal receptor, TRPA1, the same protein behind wasabi’s tingle. Garlic seems to be intertwined with capsaicin: People born without heatsensing TRPV1 can’t feel capsaicin’s burn, but they’re also hypersensitive to garlic.
Chili and garlic operate through the trigeminal nerve, but the five main tastes—sweet, salty, sour, bitter, and umami—use a whole other mechanism. For sweet, a receptor grabs an L-shaped structure common to sugar and artificial sweeteners. When any of those nestle into the groove, they start a cascade of messages that make the brain say, “Sweet!”
Unlike the lock-and-key receptors that signal sweet, salt is likely detected by ion channels on cells in your taste buds. Positively charged sodium ions (the Na in NaCl) sneak through, changing the cell’s voltage and triggering a ping to the brain. Maybe. Salty taste may also depend in part on capsaicin-catching TRPV1.
As with salt, a channel receptor telegraphs the sour taste of acetic acid. Free protons from the vinegar activate the receptor, starting a cascade of signals that transmits the tangy note that makes sriracha a chorus of deliciousness. Acidity also helps keep this sauce shelf-stable—though we know it won’t last long in your cabinet anyway.
Sriracha is a general class of Southeast Asian sauces; what makes the more famous green-capped version different is this thickener, which gives it good “cling” to tofu, eggs, or oatmeal. (Hey, we don’t judge.) But it also completes a flavor triple crown: taste, smell, and texture. Sriracha sticks to mechanoreceptors on your tongue too, sending info about creamy mouthfeel down that same trigeminal nerve—a pleasant change from the sting of capsaicin and garlic.
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Image by Jarren Vink.