Umami
Encyclopedia
Umami uːˈmɑːmi, popularly referred to as savoriness, is one of the five basic tastes together with sweet, sour, bitter, and salty.
from the Japanese meaning "pleasant savory taste". This particular writing was chosen by Professor Kikunae Ikeda
from umai (うまい) "delicious" and mi (味) "taste". In Japan, while normally written in hiragana
, the kanji
(Chinese characters) 旨味 are used for a more general meaning, when a particular food is considered to be delicious.
; but in 1985 at the first Umami International Symposium in Hawaii, the term Umami was recognized as the scientific term to describe the taste of glutamates and nucleotide
s. Now it is widely accepted as the fifth basic taste. Umami represents the taste of the amino acid L-glutamate
and 5’-ribonucleotides such as guanosine monophosphate
(GMP) and inosine monophosphate (IMP). Although it can be described as a pleasant "broth
y" or "meat
y" taste with a long lasting, mouthwatering and coating sensation over the tongue, umami has no translation. Umami is known as umami in almost all major languages, including English, Portuguese, Spanish, French, etc. The sensation of umami is due to the detection of the carboxylate anion
of glutamate
in specialized receptor cells present on the human and animal tongue
. Its fundamental effect is the ability to balance taste and round the total flavor of a dish. Umami clearly enhances the palatability of a wide variety of foods (for review Beauchamp, 2009). Glutamate in acid form (Glutamic acid) imparts little umami taste; whereas the
salts of glutamic acid
, such as monosodium glutamate, can easily ionize and give the characteristic umami taste. GMP and IMP amplify the taste intensity of glutamate.
has a long history in cooking. Fermented fish sauces (garum
), rich in glutamate, were already used in ancient Rome. In the late 1800s, chef Auguste Escoffier
, who opened what was the most glamorous, expensive, and revolutionary restaurant in Paris, created meals that combined umami with salty, sour, sweet and bitter tastes. He had not, however, known the chemical source for this unique quality.
Umami was not properly identified until 1908 by the scientist Kikunae Ikeda
, a Professor of the Tokyo Imperial University. He found that glutamate
was responsible for the palatability of the broth from kombu
seaweed. He noticed that the taste of kombu dashi
was distinct from sweet, sour, bitter and salty and named it umami.
Later, a disciple of professor Ikeda, Shintaro Kodama, discovered in 1913 that dried bonito flakes
contained another umami substance. This was the ribonucleotide IMP. In 1957, Akira Kuninaka realized that the ribonucleotide GMP present in shiitake
mushrooms also conferred the umami taste. One of Kuninaka's most important discoveries was the synergistic
effect between ribonucleotides and glutamate. When foods rich in glutamate are combined with ingredients that have ribonucleotides, the resulting taste intensity is higher than the sum of both ingredients.
This synergy of umami provides an explanation for various classical food pairings, starting with why Japanese make dashi with kombu seaweed and dried bonito flakes, and continuing with various other dishes: Chinese add Chinese leek and cabbage with chicken soup, as in the similar Scottish dish of cock-a-leekie soup
, and Italians combine Parmesan cheese on tomato sauce with mushrooms. The umami taste sensation of those ingredients mixed together surpasses the taste of each one alone.
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. In fact, Roinien et al. showed that ratings on 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.
Some population groups, such as the elderly, may benefit from umami taste because their taste and smell sensitivity is impaired by age and multiple medications. The loss of taste and smell can contribute to a poor nutritional status increasing their risk of disease.Numerous studies have indicated the beneficial effect of adding umami flavor to foods and the increased in food consumption in institutionalized elderly populations.,,
Salt reduction can improve certain disease state such hypertension. It has been suggested that umami flavor be added to food to increase the palatability of foods with reduced salt and fat.
The U.S. food and Drug Administration (FDA) classified glutamate as a Generally Recognized As Safe or GRAS. In 1987, JECFA (Joint FAO/WHO Expert Committee onf food additives) conducted a comprehensive study and found that there was no indication of adverse health effects due to consumption of glutamate in food. This study also concluded that as there were no evidence regarding the consumption of additives (such as glutamate) and infants, it recommended that additives should not be used in infants.
There is no evidence to suggest correlation between the consumption of foods containing glutamate and adverse health effects, however, many consumers would prefer not having glutamate in their foods. As indicated above, there are some foods that naturally contain glutamate, but consumers are not aware of this. Manufracturers are aware that consumers are adverse to having glutamate in their foods, and in response to this, they have begun to label foods with names that consumers will not recognize as glutamate such as "hydrolyzed soy protein".
, IMP and GMP
, most notably in fish
, shellfish
, cured meats, vegetable
s (e.g. mushrooms, ripe tomato
es, Chinese cabbage
, spinach
, etc.) or green tea
, and fermented and aged products (e.g. cheese
s, shrimp pastes, soy sauce
, etc.).
Humans' first encounter with umami is often breast milk
. It contains roughly the same amount of umami as broths.
There are some distinctions among stocks from different countries. In Japanese cuisine
, dashi
gives a very pure umami taste sensation because it is not based on meats. In dashi, L-glutamate comes from sea kombu (Laminaria japonica) and inosinate from dried bonito flakes (katsuobushi
) or small dried sardines (niboshi
). In contrast, Western or Chinese
broths have a more complex taste because of a wider mixture of amino acids from bones, meats and vegetables.
s on the tongue and other regions of the mouth can detect umami taste independently of their location. The tongue map
in which different tastes are distributed in different regions of the tongue is a common misconception. Biochemical studies have identified the taste receptor
s responsible for the sense of umami, a modified form of mGluR4
, mGluR1
and taste receptor type 1 (T1R1 + T1R3)
, and all have been found in taste buds from any region of tongue. The New York Academy of Sciences corroborated the acceptance of these receptors stating that "Recent molecular biological studies have now identified strong candidates for umami receptors, including the heterodimer T1R1/T1R3, 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 T1R1 + T1R3 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 are G protein-coupled receptors (GPCRs) with similar signaling molecules that include G protein
s beta-gamma, PLCb2
and PI3
-mediated release of calcium
(Ca2+) from intracellular stores. Ca2+ activates the selective cation channel transient receptor potential melastatin 5 (TrpM5
) that leads to membrane depolarization and the consequent release of ATP
and secretion
of neurotransmitters including serotonin
. Cells responding to umami taste stimuli do not possess typical synapses, but ATP conveys taste signals to gustatory nerves and in turn to the brain that interprets and identifies the taste quality.
fMRI studies identify the taste processing of umami in the brain to the middle insular cortex
near an area that processes the taste of salt
.
Etymology
Umami is a loanwordLoanword
A loanword is a word borrowed from a donor language and incorporated into a recipient language. By contrast, a calque or loan translation is a related concept where the meaning or idiom is borrowed rather than the lexical item itself. The word loanword is itself a calque of the German Lehnwort,...
from the Japanese meaning "pleasant savory taste". This particular writing was chosen by Professor Kikunae Ikeda
Kikunae Ikeda
was a Japanese chemist and Tokyo Imperial University professor in Chemistry who, in 1908, uncovered the chemical root behind a taste he named umami. He discovered the common component that produced the flavor of meat, seaweed and tomatoes was glutamate, which produces the sensation of umami.He also...
from umai (うまい) "delicious" and mi (味) "taste". In Japan, while normally written in hiragana
Hiragana
is a Japanese syllabary, one basic component of the Japanese writing system, along with katakana, kanji, and the Latin alphabet . Hiragana and katakana are both kana systems, in which each character represents one mora...
, the kanji
Kanji
Kanji are the adopted logographic Chinese characters hanzi that are used in the modern Japanese writing system along with hiragana , katakana , Indo Arabic numerals, and the occasional use of the Latin alphabet...
(Chinese characters) 旨味 are used for a more general meaning, when a particular food is considered to be delicious.
Background
For a long time, scientists debated whether umami was indeed a basic tasteTaste
Taste is one of the traditional five senses. It refers to the ability to detect the flavor of substances such as food, certain minerals, and poisons, etc....
; but in 1985 at the first Umami International Symposium in Hawaii, the term Umami was recognized as the scientific term to describe the taste of glutamates and nucleotide
Nucleotide
Nucleotides are molecules that, when joined together, make up the structural units of RNA and DNA. In addition, nucleotides participate in cellular signaling , and are incorporated into important cofactors of enzymatic reactions...
s. Now it is widely accepted as the fifth basic taste. Umami represents the taste of the amino acid L-glutamate
Glutamic acid
Glutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates...
and 5’-ribonucleotides such as guanosine monophosphate
Guanosine monophosphate
Guanosine monophosphate, also known as 5'-guanidylic acid or guanylic acid and abbreviated GMP, is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid with the nucleoside guanosine. GMP consists of the phosphate group, the pentose sugar ribose, and the nucleobase...
(GMP) and inosine monophosphate (IMP). Although it can be described as a pleasant "broth
Broth
Broth is a liquid food preparation, typically consisting of either water or an already flavored stock, in which bones, meat, fish, cereal grains, or vegetables have been simmered. Broth is used as a basis for other edible liquids such as soup, gravy, or sauce. It can be eaten alone or with garnish...
y" or "meat
Meat
Meat is animal flesh that is used as food. Most often, this means the skeletal muscle and associated fat and other tissues, but it may also describe other edible tissues such as organs and offal...
y" taste with a long lasting, mouthwatering and coating sensation over the tongue, umami has no translation. Umami is known as umami in almost all major languages, including English, Portuguese, Spanish, French, etc. The sensation of umami is due to the detection of the carboxylate anion
Carboxylate anion
A carboxylate is a salt or ester of a carboxylic acid.Carboxylate salts have the general formula Mn, where M is a metal and n is 1,2,...; carboxylate esters have the general formula RCOOR'. R and R' are organic groups; R'≠H....
of glutamate
Glutamic acid
Glutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates...
in specialized receptor cells present on the human and animal tongue
Tongue
The tongue is a muscular hydrostat on the floors of the mouths of most vertebrates which manipulates food for mastication. It is the primary organ of taste , as much of the upper surface of the tongue is covered in papillae and taste buds. It is sensitive and kept moist by saliva, and is richly...
. Its fundamental effect is the ability to balance taste and round the total flavor of a dish. Umami clearly enhances the palatability of a wide variety of foods (for review Beauchamp, 2009). Glutamate in acid form (Glutamic acid) imparts little umami taste; whereas the
salts of glutamic acid
Glutamic acid
Glutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates...
, such as monosodium glutamate, can easily ionize and give the characteristic umami taste. GMP and IMP amplify the taste intensity of glutamate.
Discovery of umami taste
GlutamateGlutamic acid
Glutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates...
has a long history in cooking. Fermented fish sauces (garum
Garum
Garum, similar to liquamen, was a type of fermented fish sauce condiment that was an essential flavour in Ancient Roman cooking, the supreme condiment....
), rich in glutamate, were already used in ancient Rome. In the late 1800s, chef Auguste Escoffier
Auguste Escoffier
Georges Auguste Escoffier was a French chef, restaurateur and culinary writer who popularized and updated traditional French cooking methods. He is a legendary figure among chefs and gourmands, and was one of the most important leaders in the development of modern French cuisine...
, who opened what was the most glamorous, expensive, and revolutionary restaurant in Paris, created meals that combined umami with salty, sour, sweet and bitter tastes. He had not, however, known the chemical source for this unique quality.
Umami was not properly identified until 1908 by the scientist Kikunae Ikeda
Kikunae Ikeda
was a Japanese chemist and Tokyo Imperial University professor in Chemistry who, in 1908, uncovered the chemical root behind a taste he named umami. He discovered the common component that produced the flavor of meat, seaweed and tomatoes was glutamate, which produces the sensation of umami.He also...
, a Professor of the Tokyo Imperial University. He found that glutamate
Glutamic acid
Glutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates...
was responsible for the palatability of the broth from kombu
Kombu
Kombu or konbu , also called dashima or haidai , is edible kelp from the family Laminariaceae widely eaten in East Asia....
seaweed. He noticed that the taste of kombu dashi
Dashi
Dashi is a class of soup and cooking stock, considered fundamental to Japanese cooking. In 1980, Shizuo Tsuji wrote: "Many substitutes for dashi are possible, but without dashi, dishes are merely à la japonaise and lack the authentic flavor." Dashi forms the base for miso soup, clear broth, noodle...
was distinct from sweet, sour, bitter and salty and named it umami.
Later, a disciple of professor Ikeda, Shintaro Kodama, discovered in 1913 that dried bonito flakes
Katsuobushi
is the Japanese name for dried, fermented, and smoked skipjack tuna .Shaved Katsuobushi and dried kelp - kombu - are the main ingredients of dashi, a broth that forms the basis of many soups and sauces in Japanese cuisine.Katsuobushi's distinct umami flavor comes from its high...
contained another umami substance. This was the ribonucleotide IMP. In 1957, Akira Kuninaka realized that the ribonucleotide GMP present in shiitake
Shiitake
The Shiitake is an edible mushroom native to East Asia, which is cultivated and consumed in many Asian countries, as well as being dried and exported to many countries around the world. It is a feature of many Asian cuisines including Vietnamese, Chinese, Japanese, Korean and Thai...
mushrooms also conferred the umami taste. One of Kuninaka's most important discoveries was the synergistic
Synergy
Synergy may be defined as two or more things functioning together to produce a result not independently obtainable.The term synergy comes from the Greek word from , , meaning "working together".-Definitions and usages:...
effect between ribonucleotides and glutamate. When foods rich in glutamate are combined with ingredients that have ribonucleotides, the resulting taste intensity is higher than the sum of both ingredients.
This synergy of umami provides an explanation for various classical food pairings, starting with why Japanese make dashi with kombu seaweed and dried bonito flakes, and continuing with various other dishes: Chinese add Chinese leek and cabbage with chicken soup, as in the similar Scottish dish of cock-a-leekie soup
Cock-a-leekie soup
Cock-a-leekie soup is a Scottish soup dish of leeks and chicken stock. The original recipe added prunes during cooking, and traditionalists still garnish with a julienne of prunes....
, and Italians combine Parmesan cheese on tomato sauce with mushrooms. The umami taste sensation of those ingredients mixed together surpasses the taste of each one alone.
Properties of umami taste
Umami has a mild but lasting after-taste difficult to describe. It induces salivation and a furriness sensation on the tongue, stimulating the throat, the roof and the back of the mouth (for review Yamaguchi, 1998). By itself, umami is not palatable, but it makes a great variety of foods pleasant especially in the presence of a matching aroma. But like other basic tastes, with the exception of sucrose, 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. In fact, Roinien et al. showed that ratings on 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.
Some population groups, such as the elderly, may benefit from umami taste because their taste and smell sensitivity is impaired by age and multiple medications. The loss of taste and smell can contribute to a poor nutritional status increasing their risk of disease.Numerous studies have indicated the beneficial effect of adding umami flavor to foods and the increased in food consumption in institutionalized elderly populations.,,
Salt reduction can improve certain disease state such hypertension. It has been suggested that umami flavor be added to food to increase the palatability of foods with reduced salt and fat.
The U.S. food and Drug Administration (FDA) classified glutamate as a Generally Recognized As Safe or GRAS. In 1987, JECFA (Joint FAO/WHO Expert Committee onf food additives) conducted a comprehensive study and found that there was no indication of adverse health effects due to consumption of glutamate in food. This study also concluded that as there were no evidence regarding the consumption of additives (such as glutamate) and infants, it recommended that additives should not be used in infants.
There is no evidence to suggest correlation between the consumption of foods containing glutamate and adverse health effects, however, many consumers would prefer not having glutamate in their foods. As indicated above, there are some foods that naturally contain glutamate, but consumers are not aware of this. Manufracturers are aware that consumers are adverse to having glutamate in their foods, and in response to this, they have begun to label foods with names that consumers will not recognize as glutamate such as "hydrolyzed soy protein".
Foods rich in umami
Many foods that may be consumed daily are rich in umami. Naturally occurring glutamate can be found in meats and vegetables; whereas inosinate comes primarily from meats and guanylate from vegetables. Thus, umami taste is common to foods that contain high levels of L-glutamateGlutamic acid
Glutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates...
, IMP and GMP
Guanosine monophosphate
Guanosine monophosphate, also known as 5'-guanidylic acid or guanylic acid and abbreviated GMP, is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid with the nucleoside guanosine. GMP consists of the phosphate group, the pentose sugar ribose, and the nucleobase...
, most notably in fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, shellfish
Shellfish
Shellfish is a culinary and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environments, some kinds are found only in freshwater...
, cured meats, vegetable
Vegetable
The noun vegetable usually means an edible plant or part of a plant other than a sweet fruit or seed. This typically means the leaf, stem, or root of a plant....
s (e.g. mushrooms, ripe tomato
Tomato
The word "tomato" may refer to the plant or the edible, typically red, fruit which it bears. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in greenhouses in cooler...
es, Chinese cabbage
Chinese cabbage
Chinese cabbage can refer to two distinct varieties of Chinese leaf vegetables used often in Chinese cuisine. These vegetables are both related to the Western cabbage, and are of the same species as the common turnip...
, spinach
Spinach
Spinach is an edible flowering plant in the family of Amaranthaceae. It is native to central and southwestern Asia. It is an annual plant , which grows to a height of up to 30 cm. Spinach may survive over winter in temperate regions...
, etc.) or green tea
Green tea
Green tea is made solely from the leaves of Camellia sinensis that have undergone minimal oxidation during processing. Green tea originates from China and has become associated with many cultures throughout Asia. It has recently become more widespread in the West, where black tea is traditionally...
, and fermented and aged products (e.g. cheese
Cheese
Cheese is a generic term for a diverse group of milk-based food products. Cheese is produced throughout the world in wide-ranging flavors, textures, and forms....
s, shrimp pastes, soy sauce
Soy sauce
Soy sauce is a condiment produced by fermenting soybeans with Aspergillus oryzae or Aspergillus sojae molds, along with water and salt...
, etc.).
Humans' first encounter with umami is often breast milk
Breast milk
Breast milk, more specifically human milk, is the milk produced by the breasts of a human female for her infant offspring...
. It contains roughly the same amount of umami as broths.
There are some distinctions among stocks from different countries. In Japanese cuisine
Japanese cuisine
Japanese cuisine has developed over the centuries as a result of many political and social changes throughout Japan. The cuisine eventually changed with the advent of the Medieval age which ushered in a shedding of elitism with the age of shogun rule...
, dashi
Dashi
Dashi is a class of soup and cooking stock, considered fundamental to Japanese cooking. In 1980, Shizuo Tsuji wrote: "Many substitutes for dashi are possible, but without dashi, dishes are merely à la japonaise and lack the authentic flavor." Dashi forms the base for miso soup, clear broth, noodle...
gives a very pure umami taste sensation because it is not based on meats. In dashi, L-glutamate comes from sea kombu (Laminaria japonica) and inosinate from dried bonito flakes (katsuobushi
Katsuobushi
is the Japanese name for dried, fermented, and smoked skipjack tuna .Shaved Katsuobushi and dried kelp - kombu - are the main ingredients of dashi, a broth that forms the basis of many soups and sauces in Japanese cuisine.Katsuobushi's distinct umami flavor comes from its high...
) or small dried sardines (niboshi
Niboshi
Niboshi are Japanese dried baby sardines . They are one of many varieties of small dried fish used throughout Asia in snacks and as seasoning for soup stocks and other foods....
). In contrast, Western or Chinese
Chinese cuisine
Chinese cuisine is any of several styles originating in the regions of China, some of which have become highly popular in other parts of the world – from Asia to the Americas, Australia, Western Europe and Southern Africa...
broths have a more complex taste because of a wider mixture of amino acids from bones, meats and vegetables.
Taste receptors
All taste budTaste bud
Taste buds contain the receptors for taste. They are located around the small structures on the upper surface of the tongue, soft palate, upper esophagus and epiglottis, which are called papillae. These structures are involved in detecting the five elements of taste perception: salty, sour,...
s on the tongue and other regions of the mouth can detect umami taste independently of their location. The tongue map
Tongue map
The tongue map or taste map is a common misconception that different sections of the tongue are exclusively responsible for different basic tastes. It is illustrated with a schematic map of the tongue, with certain parts of the tongue labeled for each taste...
in which different tastes are distributed in different regions of the tongue is a common misconception. Biochemical studies have identified the taste receptor
Taste receptor
A Taste receptor is a type of receptor which facilitates the sensation of taste.Examples include TAS2R16 and TAS2R38.They are divided into two families:* Type 1, sweet, first characterized in 2001: –...
s responsible for the sense of umami, a modified form of mGluR4
Metabotropic glutamate receptor 4
Metabotropic glutamate receptor 4 is a protein that in humans is encoded by the GRM4 gene.Together with GRM6, GRM7 and GRM8 it belongs to group III of the metabotropic glutamate receptor family. Group III receptors are linked to the inhibition of the cyclic AMP cascade.Activation of GRM4 has...
, mGluR1
Metabotropic glutamate receptor 1
The glutamate receptor, metabotropic 1, also known as GRM1, is a human gene which encodes the metabotropic glutamate receptor 1 protein.-Function:...
and taste receptor type 1 (T1R1 + T1R3)
Taste receptor
A Taste receptor is a type of receptor which facilitates the sensation of taste.Examples include TAS2R16 and TAS2R38.They are divided into two families:* Type 1, sweet, first characterized in 2001: –...
, and all have been found in taste buds from any region of tongue. The New York Academy of Sciences corroborated the acceptance of these receptors stating that "Recent molecular biological studies have now identified strong candidates for umami receptors, including the heterodimer T1R1/T1R3, 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 T1R1 + T1R3 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 are G protein-coupled receptors (GPCRs) with similar signaling molecules that include G protein
G protein
G proteins are a family of proteins involved in transmitting chemical signals outside the cell, and causing changes inside the cell. They communicate signals from many hormones, neurotransmitters, and other signaling factors. G protein-coupled receptors are transmembrane receptors...
s beta-gamma, PLCb2
PLCB2
1-Phosphatidylinositol-4,5-bisphosphate phosphodiesterase beta-2 is an enzyme that in humans is encoded by the PLCB2 gene. The gene codes for the enzyme phospholipase C β2. The enzyme catalyzes the formation of inositol 1,4,5-trisphosphate and diacylglycerol from phosphatidylinositol 4,5-bisphosphate...
and PI3
Inositol triphosphate
Inositol trisphosphate or inositol 1,4,5-trisphosphate , together with diacylglycerol , is a secondary messenger molecule used in signal transduction and lipid signaling in biological cells. While DAG stays inside the membrane, IP3 is soluble and diffuses through the cell...
-mediated release of calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
(Ca2+) from intracellular stores. Ca2+ activates the selective cation channel transient receptor potential melastatin 5 (TrpM5
TRPM5
Transient receptor potential cation channel subfamily M member 5 , also known as long transient receptor potential channel 5 is a protein that in humans is encoded by the TRPM5 gene....
) that leads to membrane depolarization and the consequent release of ATP
Adenosine triphosphate
Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...
and secretion
Secretion
Secretion is the process of elaborating, releasing, and oozing chemicals, or a secreted chemical substance from a cell or gland. In contrast to excretion, the substance may have a certain function, rather than being a waste product...
of neurotransmitters including serotonin
Serotonin
Serotonin or 5-hydroxytryptamine is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract, platelets, and in the central nervous system of animals including humans...
. Cells responding to umami taste stimuli do not possess typical synapses, but ATP conveys taste signals to gustatory nerves and in turn to the brain that interprets and identifies the taste quality.
fMRI studies identify the taste processing of umami in the brain to the middle insular cortex
Insular cortex
In each hemisphere of the mammalian brain the insular cortex is a portion of the cerebral cortex folded deep within the lateral sulcus between the temporal lobe and the frontal lobe. The cortical area overlying it towards the lateral surface of the brain is the operculum...
near an area that processes the taste of salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
.
External links
- Umami Information Centre (NPONon-profit organizationNonprofit organization is neither a legal nor technical definition but generally refers to an organization that uses surplus revenues to achieve its goals, rather than distributing them as profit or dividends...
) - International Glutamate Information Service
- Italian umami research
- Discovery of Umami
- Discovery of Umami Receptors
- Society for Research on Umami Taste
- "Who's umami? Human taste now comes in five flavours", CBC News, June 1, 2007
- "Sweet, Sour, Salty, Bitter… and Umami" NPR, November 1, 2007
- A New Taste Sensation, by Katy McLaughlin, Wall Street Journal, 12/8/07.
- Mouthfuls : huitlacoche is another beispiel, 24/7/08.