Umami:
http://www.umamiinfo.com/what/whatisumami/"It has been over a century since umami was discovered in Japan, but umami is just now attracting global attention, primarily from chefs and others with a strong interest in food.
Umami is the fifth taste, joining sweet, sour, salty and bitter. These are unique tastes that cannot be created by mixing other tastes, and are known as the basic, or primary tastes. Umami is a general term used mainly for substances combining the amino acid glutamate, and/or the nucleotides inosinate and guanylate, with minerals such as sodium and potassium.*
＊In scientific terms, umami is defined as the taste of salts combining glutamate, inosinate or guanylate with the likes of sodium ions, such as monosodium glutamate, or potassium ions, but for the purposes of this pamphlet, except for sections requiring scientific precision, we describe umami as the taste of glutamate, inosinate and guanylate. Salts of the amino acid aspartate and the nucleotide adenylate are also types of umami substance, weaker than glutamate. Succinic acid, which gives shellfish their distinctive taste, has also been identified as another possible umami substance."
