The human palate has long been accustomed to identifying five primary tastes: sweet, sour, salty, bitter, and umami, the savory taste attributed to foods like soy sauce and anchovies. However, in the realm of taste, science is continually evolving, and researchers at the University of Southern California (USC Dornsife) have recently proposed the existence of a potential sixth basic taste sensation: ammonium chloride. This intriguing discovery opens up a new dimension of flavor that can be detected on the tongue, bridging the realms of toxic substances and confectionery delights. The findings of this study were published in the journal Nature.
The five established basic tastes have long been familiar to all – sweet for sugary confections, sour for tangy citrus, salty for savory snacks, bitter for dark chocolate, and umami for the richness of protein-rich foods like soy sauce. However, ammonium chloride introduces an exciting twist to the taste spectrum. A prime example of this flavor is the infamous salty licorice, a beloved confectionery additive in Scandinavia, the Netherlands, and northern Germany. This unique taste imparts a complex combination of sensations, making sweet treats seem bitter and sour while retaining a salty undertone.
Researchers have known the tongue’s response to ammonium chloride for some time, but only recently have they identified the precise receptors responsible for detecting it. This breakthrough can be attributed to a specific protein called OTOP1, which responds to ammonium chloride and captures acidity found in familiar ingredients like lemon juice or vinegar. Laboratory experiments conclusively demonstrated that ammonium chloride activates the OTOP1 receptor as effectively as acid.
The implications of this discovery suggest that the ability to detect this sixth taste sensation may not be inherently essential but evolved to aid organisms in avoiding harmful substances. After all, ammonium and the associated gas ammonia are toxic to humans and animals. As Professor Emily Lyman, a specialist in Biological Sciences at the University of Southern California, noted, “Ammonium is somewhat toxic, so it makes sense that we have evolved gustatory mechanisms to detect it.”
While the concept of a sixth basic taste is tantalizing, achieving official recognition for ammonium chloride as a distinct taste sensation may be challenging. Umami, for instance, was only recognized as the fifth basic taste several decades after its initial discovery. The path to understanding the complexity of human taste buds and sensory perception is an ongoing journey, and the potential addition of a sixth taste offers an exciting opportunity for further exploration in the world of flavor science.
