Glucoerucin is mainly present in cruciferous or brassica vegetables, such as broccoli, cabbage, cauliflower, rapeseed, and mustard. The reason why arugula is bitter and spicy, and even why mustard is pungent, is in fact because they belong to the cruciferous vegetables family, which contains thioglucosides and sesquiterpene glycosides. When chewed and broken by the teeth, sesquiterpene glycosides can be hydrolyzed by their own endogenous myrosinase (black mustard enzyme) to generate sesquiterpenes. Under certain conditions, these can be converted into radish sulfide (raphanin) through interaction with sulfur-containing compounds. Both types of metabolites possess a certain degree of bitterness and strong pungent irritating odor, along with some sulfide taste characteristics.
