Taste is the sensation produced when a substance in the mouth reacts chemically with taste receptor cells located on taste buds in the oral cavity, mostly on the tongue.
You have about 10,000 buds, and not all are located on your tongue: some are found on the roof of your mouth and others in your throat, which explains why medicine is so unpleasant going down the hatch. The sensation of taste includes five established basic tastes: sweetness, sourness, saltiness, bitterness, and umami.
The combination of salty and sweet is one that shouldn’t work, but magically and deliciously does. Too much sugar is overly intense and too much salt simply tastes terrible, but when you mix the two, the combination is heavenly.
Just think of chocolate-covered pretzels: a favorite snack of sweet/salty aficionados. Pretzels are characterized by a slightly bitter taste that comes from the lye or baking soda solution the dough is soaked in before baking.
When combined, these two seemingly contradictory tastes create a unique combination that heightens the more subtle tastes and brings new complexity to the surface. Chefs call this flavor layering, and the right mix — not too sweet and not too salty — gives your brain a positive biological response.
Why is this? Lets take a look again at our example of chocolate covered pretzels:
When dusted with a bit of salt and covered in a layer of chocolate — presto! The pretzel transforms into a delightfully salty-yet-sweet treat without a hint of bitterness. Why does this happen? Sodium has been shown to orally suppress bitterness where it directly interferes with the perception of bitterness in taste pores, a phenomenon sometimes called "bitter blocking". Instead of directly enhancing sweetness, salt suppresses bitterness and therefore allows the more ‘favorable flavors,’ such as sweet, to shine through.*
Dishes that combine these two conflicting flavor directions are appearing everywhere. We can’t get enough of it. Sweetness, usually regarded as a pleasurable sensation, is produced by the presence of sugars and a few other substances. The simplest receptor found in the mouth is the sodium chloride (salt) receptor. Saltiness is a taste produced primarily by the presence of sodium ions.
Contrary to what you probably learned in elementary school, each taste bud can sense all of these. Salt’s a flavor enhancer. So, it stands to reason that if you mix sugar and salt, the salt enhances the sugar flavor.
We like sweet because it signals calories, or energy, to us. And we like salt because we need it for normal bodily function. We have no sodium storage system, as we do with other minerals (i.e. we store calcium in our bones), so Mother Nature’s solution is a built-in craving for it. The combination of these two positive biological responses is very pleasurable. To use an analogy, it’s akin to hearing beautiful music while sniffing rose petals: two positive sensory stimuli.**
And finally, because we crave sugar for the carbohydrates to keep our bodies going, and we crave salt for the essential nutrition, sweet and salty really is a perfect match.
*scienceandfood Savoring the Science of Salty and Sweet
**io9 What Makes Sugar and Salt So Delicious Together?
Photo: Helen Horstmann-Allen www.flickr.com/photos/hhbw