Why Salt Tames The Bitterness Of Grapefruit Better Than Sugar

They say our capacity to reason separates humans from the rest of the animal kingdom. But dog owners might disagree, as might food scientists, who'd argue what separates us from our four-legged fellow planet-dwellers is that we, alone, have evolved to appreciate and even seek out bitter flavors, per Slate. Chalk it up to reason if you will, but humans, alone, can distinguish between "bad bitter," i.e., the poisonous stuff that could kill us, and "good bitter," foods and beverages for which bitterness is an essential flavor component. Think of it as nature's built-in warning system.

Consider cocktails that rely on a shake or two of bitters for a well-layered flavor profile, as Binwise explains. Or, more pertinently, think about grapefruit, per CordonBleu. In addition to its zesty and slightly acidic sweetness, grapefruit delivers a distinctly bitter aftertaste, courtesy of the flavanoid, naringin, according to NPR. Grapefruit is rich in this antioxidant, even the sweetest varieties. 

Not everyone's a grapefruit fan, but 56% of Americans polled by YouGovAmerica say they are. Still, many like to sprinkle a sweetener over their open-faced grapefruit halves before slicing and spooning the bittersweet citrus fruit, via Harvest To Table. And by sweetener, we generally mean sugar, which NPR suggests has always been the most highly subscribed grapefruit topping. However, it turns out that salt is also a viable option; in fact, salt arguably tames the bitterness of grapefruit even better than sugar does.

Salt is one of the five essential flavors, per CordonBleu. In addition, salt acts as an amplifier of other flavors. However, according to a seminal 1997 research paper published in the journal "Nature," salt doesn't work its magic on all flavors equally. While salt is especially adept at intensifying sweet flavors, it diminishes the intensity of bitter flavors. Specifically, concerning both bitter and sweet foods, such as grapefruit, a sprinkle of salt imparts relative sweetness by dampening the intensity of the bitter notes, via NPR.

But can salt really tame the bitter flavor of grapefruit better than sugar? Some say it can. As Willy Street Co-op points out, sprinkling sugar on grapefruit adds sweetness (as well as empty calories), but the bitter notes remain. By contrast, sprinkling salt on your grapefruit helps make the bitter flavor of the grapefruit resonate in a less pronounced way. In other words, sprinkle sugar on grapefruit, and you're only adding more sweetness; sprinkle salt, and you're addressing the bitterness itself. As it turns out, people have been salting their grapefruit halves for at least a century, according to NPR. And the practice may go back to the 19th century when grapefruit was first grown commercially and marketed to consumers.