is sometimes called the fifth taste. It was first identified in 1908 by Professor Ikeda Kikunae of Tokyo Imperial University. Popularly referred to as “savoriness,” umami has been proposed as one of the basic tastes (in addition to sweet, sour, salty, and bitter) sensed by specialized receptor cells present on the human and animal tongue. Umami is a Japanese word meaning “flavor” or “taste.” In English, however, “brothy,” “meaty,” “savory,” or even “deliciousness” have been proposed as alternative translations. It describes the flavor common to savory foods such as meat, Parmesan cheese, soy sauce, seaweed, and mushrooms.

The umami taste is caused by the detection of the carboxylate anion of glutamic acid, a naturally occurring amino acid common in meats, cheese, broth, stock, and other protein-heavy foods. Salts of glutamic acid, known as glutamates, easily ionize to give the same carboxylate form and therefore the same taste. For this reason, they are used as flavor enhancers. While the umami taste is caused by glutamates, 5′-ribonucleotides such as guanosine and inosine monophosphate greatly enhance its perceived intensity. Since these ribonucleotides are also acids, their salts are added together with glutamates to obtain a synergistic flavor enhancement effect.

Umami tastes are initiated by specialized receptors, with subsequent steps involving secretion of neurotransmitters, including adenosine triphosphate and serotonin. Other evidence indicates that guanosine derivatives may interact with and boost the initial umami signal. Beers brewed to show notable umami character are rare, but not unknown. For example, the addition of kelp (large seaweeds belonging to the brown algae class of plants) may give an umami taste, especially in stout beer styles, where the roastiness of the malt and the bitterness is enhanced by the umami taste of the kelp. Beers properly aged on yeast sediment can develop umami-like character. See stouts. Given that hydrolyzed (heat-treated) yeast is often used as a meat-like flavoring in foods, this cannot be considered surprising. Oenologists are currently studying the possible contribution of lees (yeast sediment) contact to the development of positive umami characteristics in wine.