The recent discovery of a sixth basic taste, responding to ammonium chloride, adds to our understanding of the complexity of taste perception and highlights the cultural significance of certain flavors, such as salt licorice in Scandinavian countries.

In a groundbreaking study published in Nature Communications, researchers at USC Dornsife College of Letters, Arts and Sciences have identified a sixth basic taste. Led by neuroscientist Emily Liman, the team found that the tongue responds to ammonium chloride through the same protein receptor that signals sour taste.

While scientists have long recognized the strong response of the tongue to ammonium chloride, the specific receptors that react to it have remained elusive. Liman and her team discovered that the protein responsible for detecting sour taste, called OTOP1, also plays a role in detecting ammonium chloride.

To confirm their findings, the researchers introduced the Otop1 gene into lab-grown human cells and exposed them to acid or ammonium chloride. They observed that ammonium chloride was a strong activator of the OTOP1 channel, even more so than acids. This confirmed their hypothesis that OTOP1 responds to ammonium chloride, generating an electrical signal in taste bud cells.

Further experiments with mice showed that taste bud cells from normal mice responded to ammonium chloride, while those lacking OTOP1 did not. This provided additional evidence that OTOP1 is responsible for detecting the taste of ammonium chloride.

The cultural significance of this discovery lies in the popularity of salt licorice, a candy that has been enjoyed in Scandinavian countries for decades. Salt licorice contains salmiak salt, which is made from ammonium chloride. The fact that the tongue has a specific receptor for this taste suggests that it may have evolved as a response to the consumption of foods containing ammonium chloride.

This research not only expands our understanding of taste perception but also highlights the cultural and regional preferences for certain flavors. The recognition of a sixth basic taste adds depth to our understanding of the intricate world of flavors and how they shape our culinary experiences.