Researchers may have discovered a sixth taste. In addition to sweet, salty, bitter, sour and umami, scientists have named another category of taste that responds to ammonium chloride, a chemical commonly found in Scandinavian candy. Researchers from USC Dornsife College of Letters, Arts and Sciences found evidence of a sixth taste after investigating the taste buds of normal mice and those of mice that had been genetically modified to not produce the OTOP1 protein, which respond to the sour taste of vinegar or lemon.