Umami

Umami(/uːˈmɑːmi/fromJapanese:うま味Japanese pronunciation:[ɯmami]), orsavoriness, is one of the fivebasic tastes.It is characteristic ofbrothsand cooked meats.
People taste umami throughtaste receptorsthat typically respond toglutamatesandnucleotides, which are widely present in meat broths and fermented products. Glutamates are commonly added to some foods in the form ofmonosodium glutamate(MSG), and nucleotides are commonly added in the form ofdisodium guanylate,inosine monophosphate(IMP) orguanosine monophosphate(GMP).Since umami has its own receptors rather than arising out of a combination of the traditionally recognized taste receptors, scientists now consider umami to be a distinct taste.
Foods that have a strong umami flavor include meats,shellfish, fish (includingfish sauceand preserved fish such asMaldives fish,katsuobushi,sardines, andanchovies),dashi,tomatoes,mushrooms,hydrolyzed vegetable protein,meat extract,yeast extract,kimchi,cheeses, andsoy sauce.
Aloanwordfrom Japanese(うま味),umamican be translated as "pleasant savory taste".Thisneologismwas coined in 1908 by Japanese chemistKikunae Ikedafrom anominalizationofumai(うまい) "delicious". The compound旨味(withmi(味) "taste") is used for a more general sense of a food as delicious.There is no English equivalent toumami; however, some close descriptions are "meaty", "savory", and "broth-like".
Scientists have debated whether umami was a basictastesince Kikunae Ikeda first proposed its existence in 1908.In 1985, the termumamiwas recognized as the scientific term to describe the taste ofglutamatesandnucleotidesat the first Umami International Symposium in Hawaii.Umami represents the taste of theamino acidL-glutamateand 5'-ribonucleotidessuch asguanosine monophosphate(GMP) andinosine monophosphate(IMP).It can be described as a pleasant "brothy" or "meaty" taste with a long-lasting, mouthwatering and coating sensation over the tongue.
The sensation of umami is due to the detection of thecarboxylate anionofglutamatein specialized receptor cells present on human and other animaltongues.Some 52peptidesmay be responsible for detecting umami taste.Umami enhances the palatability of a wide variety of foods.
Glutamate in acid form (glutamic acid) imparts little umami taste, whereas thesaltsofglutamic acid, known asglutamates, give the characteristic umami taste due to their ionized state. GMP and IMP amplify the taste intensity of glutamate.Adding salt to the free acids also enhances the umami taste.It is disputed whether umami is truly an independent taste because standalone glutamate withouttable saltions(Na+) is perceived as sour; sweet and umami tastes share a taste receptor subunit, with salty taste blockers reducing discrimination between monosodium glutamate and sucrose; and some people cannot distinguish umami from a salty taste.
MonosodiumL-aspartatehas an umami taste about four times less intense than MSG, whereasibotenic acidandtricholomic acid(likely as their salts or with salt) are claimed to be many times more intense.
Glutamatehas a long history in cooking.Fermented fish sauces (garum), which are rich in glutamate, were used widely in ancient Rome,fermented barley sauces (murri) rich in glutamate were used in medievalByzantineandArabcuisine,and fermentedfish saucesandsoy sauceshave histories going back to the third century in China. Cheese varieties are rich in glutamate and umami flavor.In the late 1800s, chefAuguste Escoffier, who opened restaurants in Paris and London, created meals that combined umami withsalty,sour,sweet, andbittertastes.However, he did not know the chemical source of this unique quality.
Umami was first scientifically identified in 1908 byKikunae Ikeda,a professor of theTokyo Imperial University. He found thatglutamatewas responsible for the palatability of the broth fromkombuseaweed. He noticed that the taste ofkombudashiwas distinct from sweet, sour, bitter, and salty and named itumami.
Professor Shintaro Kodama, a disciple of Ikeda, discovered in 1913 thatdried bonito flakes(a type of tuna) contained another umami substance.This was the ribonucleotideIMP. In 1957, Akira Kuninaka realized that the ribonucleotide GMP present inshiitakemushrooms also conferred the umami taste.One of Kuninaka's most important discoveries was thesynergisticeffect between ribonucleotides and glutamate. When foods rich in glutamate are combined with ingredients that have ribonucleotides, the resulting taste intensity is higher than would be expected from merely adding the intensity of the individual ingredients.
This synergy of umami may help explain various classical food pairings: the Japanese makedashiwithkombuseaweed and dried bonito flakes; the Chinese addChinese leekandChinese cabbageto chicken soup, as do Scots in the similar Scottish dish ofcock-a-leekie soup; and Italians grate theParmigiano-Reggianocheese on a variety of different dishes.
Umami has a mild but lasting aftertaste associated with salivation and a sensation of furriness on the tongue, stimulating the throat, the roof and the back of the mouth.By itself, umami is notpalatable, but it makes a great variety of foods pleasant, especially in the presence of a matching aroma.Like other basic tastes, umami is pleasant only within a relatively narrow concentration range.
The optimum umami taste depends also on the amount of salt, and at the same time, low-salt foods can maintain a satisfactory taste with the appropriate amount of umami.One study showed that ratings of pleasantness, taste intensity, and ideal saltiness of low-salt soups were greater when the soup contained umami, whereas low-salt soups without umami were less pleasant.Another study demonstrated that usingfish sauceas a source of umami could reduce the need for salt by 10–25% to flavor such foods aschicken broth,tomato sauce, or coconutcurrywhile maintaining overall taste intensity.
Some population groups, such as the elderly, may benefit from umami taste because their taste and smell sensitivity may be impaired by age and medication. The loss of taste and smell can contribute to poor nutrition, increasing their risk of disease.Some evidence exists to show umami not only stimulates appetite, but also may contribute tosatiety.
Many foods are rich in the amino acids and nucleotides imparting umami. Naturally occurring glutamate can be found in meats and vegetables.Inosine(IMP) comes primarily from meats andguanosine(GMP) from vegetables. Mushrooms, especially driedshiitake, are rich sources of umami flavor from guanylate. Smoked or fermented fish are high in inosinate, andshellfishinadenylate.Protein in food is tasteless, however processes such as fermentation, curing, or heat treatment release glutamate and other amino acids.
Generally, umami taste is common to foods that contain high levels ofL-glutamate,IMPandGMP, most notably infish,shellfish,cured meats,meat extracts,mushrooms,vegetables(e.g., ripetomatoes,Chinese cabbage,spinach,celery, etc.),green tea,hydrolyzed vegetable protein, and fermented and aged products involving bacterial or yeast cultures, such ascheeses,shrimp pastes,fish sauce,soy sauce,natto,nutritional yeast, andyeast extractssuch asVegemiteandMarmite.
Studies have shown that the amino acids inbreast milkare often the first encounter humans have with umami. Glutamic acid makes up half of the free amino acids in breast milk.
Since all umami taste compounds are sodium salts, the perceptual differentiation of salty and umami tastes has been difficult in taste tests and studies have found as much as 27% of certain populations may be umami "hypotasters".
Furthermore single glutamate (glutamic acid) with no table salt ions (Na+) elicits sour taste and in psychophysical tests, sodium or potassium salt cations seem to be required to produce a perceptible umami taste.
Sweet and umami tastes both utilize the taste receptor subunitTAS1R3, with salt taste blockers reducing discrimination between monosodium glutamate and sucrose in rodents.
If umami doesn't have perceptual independence, it could be classified with other tastes like fat, carbohydrate, metallic, and calcium, which can be perceived at high concentrations but may not offer a prominent taste experience.
Mosttaste budson the tongue and other regions of the mouth can detect umami taste, irrespective of their location. (Thetongue mapin which different tastes are distributed in different regions of the tongue is a common misconception.)Biochemicalstudies have identified thetaste receptorsresponsible for the sense of umami as modified forms ofmGluR4,mGluR1, andtaste receptortype 1 (TAS1R1+TAS1R3), all of which have been found in all regions of the tongue bearing taste buds.These receptors are also found in some regions of theduodenum.A 2009 review corroborated the acceptance of these receptors, stating, "Recent molecular biological studies have now identified strong candidates for umami receptors, including the heterodimer TAS1R1/TAS1R3, and truncated type 1 and 4 metabotropic glutamate receptors missing most of the N-terminal extracellular domain (taste-mGluR4 and truncated-mGluR1) and brain-mGluR4."
Receptors mGluR1 and mGluR4 are specific to glutamate whereas TAS1R1 + TAS1R3 are responsible for the synergism already described by Akira Kuninaka in 1957. However, the specific role of each type of receptor in taste bud cells remains unclear. They areG protein-coupled receptors(GPCRs) with similar signaling molecules that includeG proteins beta-gamma,PLCB2andPI3-mediated release ofcalcium(Ca) from intracellular stores.Calcium activates a so-called transient-receptor-potential cation channelTRPM5that leads to membranedepolarizationand the consequent release ofATPandsecretionofneurotransmittersincludingserotonin.
Cells responding to umami taste stimuli do not possess typicalsynapses, but ATP conveys taste signals to gustatory nerves and in turn to thebrainthat interprets and identifies the taste quality via thegut-brain axis.
Umami has become popular as a flavor with food manufacturers trying to improve the taste of low sodium offerings.Chefs create "umami bombs", which are dishes made of several umami ingredients likefish sauce.Umami may account for the long-term formulation and popularity ofketchup.The United StatesFood and Drug Administrationhas designated the umami enhancermonosodium glutamate(MSG) as a safe ingredient. While some people identify themselves assensitive to MSG, a study commissioned by the FDA was only able to identify transient, mildsymptomsin a few of the subjects, and only when the MSG was consumed in unrealistically large quantities.There is also no apparent difference in sensitivity to umami when comparing Japanese and Americans.
The five basic tastes (saltiness, sweetness, bitterness, sourness, and savoriness) are detected by specialized taste receptors on the tongue andpalateepithelium.The number of taste categories in humans remains under research, with a sixth taste possibly including spicy or pungent.