Umami is one of the five basic tastes together with sweet, sour, bitter and salty. It comes from the Japanese term umai (うまい) ‘delicious’ and mi (味) 'taste', that represents the taste imparted by the amino acid L-glutamate and 5’-ribonucleotides such as guanosine monophosphate (GMP) and inosine monophosphate (IMP).
It describes a pleasant "brothy" or "meaty" taste with a long lasting, mouthwatering and coating sensation over the tongue. This is due to the detection of the carboxylate anion of glutamic acid in specialized receptor cells present on the human and animal tongue. Its fundamental effect is the ability to balance and round the total flavour of a dish. Umami clearly enhances the palatability of soups and a wide variety of foods that are not sweet. Fruits, fruit juices and some dairy products do not match well with umami taste. Salts of glutamic acid, known as glutamates, easily ionise to give the same taste and they are used as flavour enhancers. While the umami taste is due to glutamates, (GMP) and (IMP) greatly enhance its perceived intensity.
Umami increases palatability, salivation, and can reduce considerably the use of salt (sodium chloride) without compromising taste acceptability. It can be especially useful to improve the palatability of foods low in fat or rich in vegetables. Moreover, recent research suggests that umami substances can improve protein digestion and absorption of essential amino acids.
Foods rich in umami
Many foods that we consume daily are rich in umami. Our first encounter with umami is with mother’s milk. Breast milk contains roughly the same amount of umami as Japanese broths or bouillon, called dashi. Umami taste is common to foods that contain high levels of L-glutamate, IMP and GMP, most notably in fish, cured meats, vegetables (e.g. mushrooms, ripe tomatoes) or green tea, and fermented and aged products (e.g. cheeses, shrimp pastes, soy sauce, etc).
Japanese dashi gives a very pure umami taste sensation because of its high content of L-glutamate from sea kombu (Laminaria japonica) and inosinate from dried bonito flakes (katsuobushi) or small dried sardines (niboshi). Western broths and bouillons give a more complex taste because of a wider mixture of amino acids from bones, meats and vegetables.