North of the white sausage equator runs another dividing line that divides Germany in terms of taste. It should roughly run along the Main near Frankfurt. Many licorice fans live to the north, but in the south there are fewer fans of the black candy.
Opinions differ even when it comes to simple licorice, which is made from the roots of real licorice. Even more controversial is the version with a salty-spicy note, which contains ammonium chloride – also known as salmiac. Popular in Scandinavia and the Netherlands, salt licorice is a horror for many in Germany. It has to be there since October 2021 according to regulation be explicitly labeled as “adult licorice” because ammonium chloride in higher doses can be harmful to health.
Why does adult licorice have its fans? Maybe they have a more developed sixth sense. Researchers at the University of Southern California in Los Angeles claim to have found another sensory quality. In addition to sweet, salty, sour, bitter and umami, the human tongue also reacts to ammonium chloride, they write in a study in the journal Nature Communications has appeared. The taste of the colorless salt can best be described as bitter-salty-sour.
It has long been known that the tongue reacts to ammonium chloride. But not exactly which receiver molecule (receptor) is responsible for it. The research team has now been able to show that ammoniac activates a receptor on sensory cells that is already known to also detect sour tastes. This cannot only be observed in cell cultures: the behavior of mice actually changed depending on whether they had the ammonia receptor. When it worked, the mice avoided water with ammonium chloride added. If it didn’t work, the animals weren’t put off by the taste of the ammonia water.
Perhaps the ability to taste ammonium chloride is a valuable protective mechanism. The ammonia receptor has been preserved throughout evolution; it is found in nematodes, fruit flies, chickens, mice – and in humans. Metabolites of ammonium chloride could be toxic in high doses, says Emily Liman, leader of the study: “It therefore makes sense that we have developed taste mechanisms to detect it.” How sensitive living beings are to the taste of ammonia depends largely on the environment in which they live. However, the study was unable to answer to what extent this explains the German licorice equator.
It remains to be seen whether ammonium chloride will soon be accepted as a sixth taste alongside sweet, sour, salty, bitter and umami. Sometimes it can take a long time, as the example of the meaty, spicy umami taste shows. The Japanese chemistry professor Kikunae Ikeda identified this sensory quality as early as 1908 and named it from the Japanese words “umai” meaning “spicy, savory” and “mi” meaning “taste”. Other scientists at the time received this with only moderate enthusiasm: First In 1985, during a symposium in Hawaii, umami became the fifth flavor to receive international recognition.