Buzz
Ever bitten into a lemon and felt your face scrunch up? Highly sour foods, which are rich in acid, can trigger a pucker—causing your face to wrinkle, your eyes to squint, and your lips to press together. When foods like lemons, vinegar, or unripe fruit hit your tongue, your brain recognizes the sour taste. It might be your body's way of saying, 'Be cautious!'
Your tongue is covered with thousands of tiny bumps that contain taste buds, which detect flavors like sweet, salty, sour, bitter, and savory. (Savory is also known as umami. Say: ooo-MOM-eee.) Each taste bud houses numerous taste cells with tiny hair-like structures, visible only through a microscope. When these taste cells encounter dissolved food particles in your saliva, they send signals to your brain about the food's flavor. If the food is very sour, like lemons, the taste can trigger a facial pucker because of its intensity and acidity.
Puckering in response to sour tastes is usually involuntary (in-VAWL-uhn-ter-ee). This means it happens automatically, without conscious effort. This reaction may stem from an innate instinct to avoid potentially harmful foods. While not all sour foods are dangerous, some, such as spoiled milk or unripe fruit, can make us sick. The face-wrinkling reflex might be our body's way of signaling a warning to avoid foods that could be harmful.
For more information, visit “Why Are Lemons Sour?” on Wonderopolis.
