Chocolate-covered pretzels, caramel popcorn, peanut butter and jelly, pineapple pizza, salt on watermelon (yes, it’s a thing) - sweet and salty is a pairing made in food heaven. The combination is found nearly everywhere to the point where, on the surface, the two make perfect sense, but think it over and it’s not necessarily obvious why these two flavors work so well.

Why don’t these two flavors clash? Scientists from Monell Chemical Senses Center in Philadelphia and Utah State University set out to answer this very question.

To understand their results, we first need to understand how we taste. When we put something into our mouth, components of the food associated with the five flavors – sweet (sugars), salty (salt), sour (acids like lemons and vinegar), bitter (like coffee and unsweetened cocoa) and umami (earthy and savory like cheese and mushrooms) – each activate the taste buds in our mouth.

A common misconception is that a given taste bud detects a single flavor and the five different types of taste buds are each focused in a different part of the mouth. In other words, some incorrectly believe that the left side of your mouth only detects one particular flavor. However, taste buds are composed of numerous receptors that actually detect each of the flavors. Think of the common childhood toy with the different shaped holes as a taste bud with different kinds of receptors (holes) – the star can only go through the star slot, but at other locations on the same toy, there are holes for circles and squares.

Taste buds themselves have varying degrees of sensitivity for each of the flavors, depending on how many of these receptors for a given flavor are present (continuing with the toy analogy – some toys might have five star slots and only one square and circle). When a receptor touches its respective flavor, it sends a signal to your brain telling you what flavor you’ve experienced. In other words, when you eat a piece of lemon cheesecake, even if you just burned the left side of your tongue with a sip of hot coffee, you can still experience the sweet, sour and umami flavors of the sugar, lemon and cheese, though one or two flavors may seem stronger than the others.

So why exactly am I supposed to put a pinch of salt into baked goods? As it turns out, our taste buds are more complex than we thought.

The study published in the “Proceedings of the National Academy of Sciences” by those scientists I mentioned found certain taste buds have receptors that only sense sweetness in the presence of salt. In terms of the toy, this means a star can only go through if you also put a circle through. These receptors, called SGLT1, send their “sweet” message to the brain only when salt is present, intensifying the sweetness you experience (but not in the same way that eating more sugar would).

So the next time your friend puts a pinch of salt on watermelon, there’s no need to give them a strange look, perhaps give it a try – your taste buds might surprise you.