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International Journal of Medicinal Mushrooms, Vol. 7, pp. 119–125 (2005)
1521-9437/05 $35.00
© 2005 by Begell House, Inc. 119
The Umami Taste of Edible and Medicinal Mushrooms
Jeng-Leun Mau
Department of Food Science, National Chung-Hsing University, Taichung, Taiwan, ROC
Address all correspondence to Jeng-Leun Mau, Department of Food Science, National Chung-Hsing University, 250 Kuokuang
Road, Taichung 40227, Taiwan, ROC; jlmau@dragon.nchu.edu.tw
ABSTRACT: Mushrooms impart to food the second functionality of tasty properties. e typical mush-
room fl avor consists of water-soluble taste components including free amino acids and 5′-nucleotides.
e umami taste, also called the palatable taste, is an overall food fl avor induced or enhanced by mono-
sodium glutamate (MSG). e umami taste of mushrooms can be greatly increased by the synergistic
eff ect of umami 5′-nucleotides and umami amino acids. e equivalent umami concentration (EUC) is
the concentration of MSG equivalent to the umami intensity of that given by the mixture of MSG and
the 5′-nucleotide. is article summarizes the results of mushroom taste components from a decade
of research, and calculates the EUC values of the fruit bodies and mycelia. EUC values are grouped
into four levels: >1000% (>10 g MSG/g dry matter), 100–1000% (1–10 g MSG/g), 10–100% (0.1–1 g
MSG/g), and 10% (<0.1 g MSG/g). ese EUC values are of great interest for fruit bodies and mycelia
to be used as foods or food-fl avoring materials or in the formulation of health foods.
KEY WORDS: mushrooms, umami, amino acid, 5′-nucleotide
ABBREVIATIONS
5ⴕ-AMP: 5′-adenosine monophosphate; 5ⴕ-CMP: 5′-cytosine monophosphate; 5ⴕ-GMP: 5′-guanosine monophosphate;
5ⴕ-IMP: 5′-inosine monophosphate; 5ⴕ-UMP: 5′-uridine monophosphate; 5ⴕ-XMP: 5′-xanthosine monophosphate;
Asp: Aspartic; EUC: equivalent umami concentration; Glu: glutamic acids; MSG: monosodium glutamate; RUC:
relative umami concentration
INTRODUCTION
Mushrooms, the edible species of a large group of the
higher fungi, are produce of high quality and high eco-
nomic value. Generally, mushrooms possess all three
functionalities of food—nutrition, taste, and physio-
logical functionalities. For the fi rst functionality of nu-
tritional value, mushrooms are rich in polysaccharides,
proteins, chitin, vitamin D₂, and minerals; low in fat
and calories; and contain no cholesterols (Crisan and
Sands, 1978; Chang and Miles, 1989). For the second
functionality of taste, mushrooms become delicious
food and food fl avoring substances because of their
unique fl avor. In addition to the volatile eight-carbon
compounds such as 1-octen-3-ol and 1-octen-3-one
(Maga, 1981), the typical mushroom fl avor consists of
water-soluble taste components including free amino
acids and 5′-nucleotides (Litchfi eld, 1967). For the
third functionality of physiological eff ects, with sev-
eral physiologically active substances contained therein
(Wasser and Weis, 1999), mushrooms become a valu-
able health food.
TASTE COMPONENTS IN MUSHROOMS
Taste components present in mushrooms are soluble
sugars and polyols, organic acids, free amino acids,
120 International Journal of Medicinal Mushrooms
J. L. MAU
and 5′-nucleotides. Chen (1986) conducted a se-
ries of sensory evaluations on synthetic mushroom
extracts prepared by the omission and addition
of soluble components and found the that major
taste-active components in common mushrooms
(Agaricus bisporus) are mannitol, oxalic, malic, citric,
aspartic, glutamic acids, glycine, threonine, alanine,
5'-inosine monophosphate (5′-IMP), 5′-guanosine
mono phosphate (5′-GMP), and 5′-xanthosine
mono phosphate (5′-XMP). Mannitol and organic
acids contribute most to the sweet and sour tastes,
respectively (Litchfi eld, 1967). However, they are not
the taste characteristic of mushroom fl avor.
e predominant fl avor of mushrooms is the
umami taste, also called the palatable taste or the
perception of satisfaction, which is an overall food
fl avor induced or enhanced by monosodium glu-
tamate (MSG) (Yamaguchi, 1979). In addition to
four basic tastes such as sour, sweet, bitter, and
salty tastes, as well as hot taste, the umami taste
is the sixth taste in mouth perception. MSG can
alleviate a salty, sour, or bitter taste; enhance the
perception of a sweet taste; and lower the sharp
irritation of onion, the raw odor of meat, and the
earthy note of potatoes. As a result of the proper-
ties of MSG, mushrooms can be widely used in
most foods such as meat, seafood, soup, stews, and
cooked vegetables. However, mushrooms cannot
improve the taste of fruits, juices, desserts, and
cooked cereals.
MAJOR COMPONENTS FOR UMAMI
TASTE AND THEIR SYNERGISTIC EFFECT
Mushrooms contain considerably high amounts of
free amino acids, which impart the food taste with a
smooth feeling, thereby softening a sharp taste from
some substances. erefore, the combination of free
amino acids always gives rise to a unique natural
fl avor. On the basis of their fl avor characteristics
as described by Komata (1969), free amino acids
are grouped into four classes of taste components,
including MSG-like, sweet, bitter, and tasteless
components. Chen (1986) found that sweet com-
ponents (alanine, glycine, and threonine) and MSG-
like components (Aspartic [Asp] and glutamic [Glu]
acids) were taste-active amino acids in mushrooms,
whereas none of the bitter components were found
to be taste active. e bitter taste from bitter com-
ponents might be eliminated or suppressed by the
soluble sugars and polyols and sweet components.
Because they give the most typical mushroom
taste, MSG-like components Asp and Glu are also
called umami amino acids, and their relative umami
intensities are showed in Table 1 (Yamaguchi et al.,
1971). Six 5′-nucleotides are usually detected in
mushrooms, including 5′-adenosine monophosphate
(5′-AMP), 5′-cytosine monophosphate (5′-CMP),
5′-GMP, 5′-IMP, 5′-uridine monophosphate (5′-
UMP), and 5′-XMP. Among these 5′-nucleotides,
four—5′-AMP, 5′-IMP, 5′-GMP and 5′-XMP—are
also called umami 5′-nucleotides, and their relative
umami intensities are also showed in Table 1.
5′-GMP gives a meaty fl avor and is a much
stronger fl avor enhancer than MSG (Litchfi eld,
1967). In addition, the synergistic eff
ect of umami
5′-nucleotides and umami amino acids may greatly
increase the umami taste of mushrooms (Yamaguchi
et al., 1971). After sensory evaluation and correla-
tion analysis, Yamaguchi (1967) demonstrated that
the synergistic eff ect of 5′-IMP and MSG can be
elucidated as an equation as follows:
Y = u + ruv
where Y (%) is the equivalent umami concentration
(EUC) of the solution in terms of g MSG/100 g;
TABLE 1. Relative Umami Concentration
(RUC) for Umami Amino Acids and Umami 5ⴕ-
Nucleotides*
Umami amino acid RUC
Glutamic acid, MSG (Glu) 1
Aspartic acid (Asp) 0.077
Umami 5′-nucleotide RUC
5′-Inosine monophosphate (5′-IMP) 1
5′-Guanosine monophosphate (5′-GMP) 2.3
5′-Xanthosine monophosphate (5′-XMP) 0.61
5′-Adenosine monophosphate (5′-AMP) 0.18
* Yamaguchi et al., 1971
Volume 7, Issues 1&2, 2005 121
UMAMI TASTE OF EDIBLE AND MEDICINAL MUSHROOMS
u (%) is the concentration of MSG in solution; v
(%) is the concentration of 5′-IMP; and r is a syn-
ergistic constant 1218 based on the concentration
of g/100 g used.
e EUC value is the concentration of MSG
equivalent to the umami intensity of that given by
the mixture of MSG and the 5′-nucleotide. Since
the intensity of the umami taste is additive, the above
equation can be modifi ed to apply to all umami
amino acids and umami 5′-nucleotides. erefore,
the additive equation is used to assess the overall
EUC value of MSG perceived in solution (Yama-
guchi et al., 1971):
Y = Σaibi + 1218 (Σaibi) (Σajbj)
where ai (%) is the concentration of the respective
umami amino acid (Asp or Glu); a
j (%) is the
concentration of the respective umami 5′-nucleotide
(5′-MP, 5′-GMP, 5′-XMP, or 5′-AMP); bi is the
relative umami concentration (RUC) for umami
amino acids to MSG; and bj is the RUC for umami
5′-nucleotides to 5′-IMP (Table 1).
THE EUC VALUE OF FRUIT BODIES
Currently there are all varieties of fresh and dried
mushrooms available in Taiwan. is article sum-
marizes the results of mushroom taste components
from a decade of research and calculates the EUC
values of the fruit bodies and mycelia for each
mushroom studied, using the above additive equa-
tion, which are shown in Tables 2 and 3, respectively.
e EUC value is expressed as the percentage of dry
matter by weight. An EUC value of 100% indicates
that the umami intensity of fruit bodies or mycelia
per 1 g dry matter is equivalent to the umami in-
tensity given by 1 g of MSG—in other words, 1 g
MSG/g dry matter.
As shown in Table 2, the EUC values of fruit
bodies varied widely and ranged from the highest
value of 4465% (Volvariella volvacea fl at cap) to the
lowest value of 0.12% (Auricularia polytricha). EUC
values are grouped into four levels: >1000% (>10 g
MSG/g dry matter), 100–1000% (1–10 g MSG/g),
10–100% (0.1–1 g MSG/g), and 10% (<0.1 g MSG/
g). Mushrooms with EUC values at the fi rst level
are Volvariella volvacea (paddy straw mushrooms)
and Agaricus bisporus. e EUC values of V. volva-
cea dramatically increased with cap opened. During
postharvest storage at 12 °C, the EUC value of A.
bisporus signifi cantly increased from 1144% at day
0, to 2490% at day 3, 2972% at day 6, 2653% at day
9, and 3871% at day 12 (Tseng and Mau, 1999).
However, A. bisporus is not shelf-stable for 12 days
at 12 °C. After 9 days of storage, mushrooms lost
their appeal and become unacceptable due to tissue
deterioration and microbial growth. Between days 0
and 6 at 12 °C, mushrooms are good for consump-
tion, and their EUC values were in the range of
1144–2972%.
e EUC values of fruit bodies at the second
and third levels are commercial mushroom products,
including fresh or imported dried products. ese
mushrooms are famous not exclusively because of
their umami taste, but rather partially because of
various culinary qualities such as unique fl avor,
consistency, and texture. Among them, Pleurotus
citrinopileatus and Agaricus brasiliensis (=A. blazei
ss. Heinem.) show their own unique fl avor in addi-
tion to the umami taste.
Among the EUC values of Pleurotus species, P.
citrinopileatus was the highest (511% at the second
level), and the others were in the descending order of
P. eryngii small fruit body (97.9% at the third level),
P. cystidiosus (85.2%), and P. ostreatus (48.0%). Based
on the forms of fruit bodies in cultivation bottles
or plastic bags (logs), the EUC values of P. eryngii
were 68.7, 97.9 and 32.1% for large and small fruit
bodies and base, respectively.
Currently, two strains of Flammulina velutipes
are commercially available, and their EUC values
were 363 and 139% for yellow and white strains,
respectively. Likewise, three varieties of Agrocybe
cylindracea were studied, but their EUC values were
considerably diff erent. In addition, a similar pattern
was observed on Lentinus edodes (271 and Tainung
1), whose RUC values were at the second and
third levels, respectively. erefore, upon choosing
mushrooms, the EUC value is a valuable criterion
for their taste.
e EUC values of fruit bodies at the fourth level
were mainly medicinal and ear mushrooms. It seems
122 International Journal of Medicinal Mushrooms
J. L. MAU
TABLE 2. Equivalent Umami Concentration (EUC) for Fruit Bodies
Fruit body EUC (% dry wt) Reference
Volvariella volvacea (fl at cap) 4465 Mau et al. (1997)
Volvariella volvacea (stipe elongated) 2593 Mau et al. (1997)
Volvariella volvacea (volva broken) 2198 Mau et al. (1997)
Volvariella volvacea (egg shape) 1181 Mau et al. (1997)
Agaricus bisporus (Tainung 3) 1144 Tseng and Mau (1999)
Volvariella volvacea (bell shape) 1048 Mau et al. (1997)
Pleurotus citrinopileatus 511 Huang (2003)
Flammulina velutipes (yellow) 363 Yang et al. (2001)
Hypsizygus marmoreus 272 Lee (2003)
Agrocybe cylindracea (Brown) 164 Mau and Tseng (1998)
Flammulina velutipes (white) 139 Yang et al. (2001)
Agaricus blazei 136 Tsai (2004)
Lentinus edodes (271) 132 Yang et al. (2001)
Coprinus comatus 103 Tsai (2004)
Agrocybe cylindracea (golden) 100 Mau and Tseng (1998)
Pleurotus eryngii (small fruit body) 97.9 Mau et al. (1998a)
Pleurotus cystidiosus 85.2 Yang et al. (2001)
Dictyophora indusiata 72.7 Mau et al. (2001b)
Pleurotus eryngii (large fruit body) 68.7 Mau et al. (1998a)
Agrocybe cylindracea (white) 68.1 Mau and Tseng (1998)
Pleurotus ostreatus 48.0 Yang et al. (2001)
Agrocybe cylindracea (yellow) 46.7 Tsai (2004)
Tricholoma giganteum 38.7 Mau et al. (2001b)
Pleurotus eryngii (fruit body base) 32.1 Mau et al. (1998a)
Lentinus edodes (Tainung 1) 23.4 Yang et al. (2001)
Grifola frondosa 12.7 Mau et al. (2001b)
Boletus edulis 10.5 Tsai (2004)
Ganoderma lucidum 7.92 Mau et al. (2001a)
Trametes versicolor 7.70 Mau et al. (2001a)
Ganoderma tsugae (baby Ling chih) 5.43 Tseng et al. (2004)
Auricularia fuscosuccinea (white) 4.11 Mau et al. (1998b)
Hericium erinaceus 3.00 Mau et al. (2001b)
Ganoderma lucidum (antler) 2.58 Mau et al. (2001a)
Auricularia fuscosuccinea (brown) 2.38 Mau et al. (1998b)
Auricularia mesenterica 1.52 Mau et al. (1998b)
Ganoderma tsugae 0.97 Mau et al. (2001a)
0.66 Tseng et al. (2004)
Tremella fuciformis 0.49 Mau et al. (1998b)
Auricularia polytricha 0.12 Mau et al. (1998b)
Volume 7, Issues 1&2, 2005 123
UMAMI TASTE OF EDIBLE AND MEDICINAL MUSHROOMS
TABLE 3. Equivalent Umami Concentration (EUC) for Mycelia
Mycelia EUC (% dry wt) Reference
Termitomyces albuminosus 460 Wen (2003)
Grifola frondosa 375 Wen (2003)
Morchella esculenta 363 Wen (2003)
Hypsizygus marmoreus 128 Lee (2003)
Cordyceps militaris 124 Chang et al. (2001)
Pleurotus citrinopileatus 37.1 Huang (2003)
Antrodia camphorata 21.2 Chang et al. (2001)
Ganoderma tsugae 19.4 Tseng et al. (2004)
Agaricus brasiliensis 1.92 Chang et al. (2001)
that their EUC values were listed for information
only. Ear mushrooms for use in foods are dried prod-
ucts, and they provide bite and chew texture instead
of the umami taste after dehydration and cooking.
Because the EUC values of medicinal mushrooms
were low, the taste of these medicinal mushrooms
should be taken into consideration as their applica-
tion in the formulation of health foods. In addition
to their low EUC values, medicinal mushrooms
are bitter in nature because of the presence of the
biologically active components bitter triterpenoids
(Shao et al., 1994).
Fresh fruit bodies generally contained 85–93%
moisture (Chang and Miles, 1989). In order to
show a consistent comparison on the same basis,
the data were calculated based on dry matter. Upon
the conversion of the dry basis to the fresh basis,
the moisture content of Agaricus bisporus was ar-
bitrarily assigned to be 90%. erefore, the EUC
value (% fresh matter) of A. bisporus was 114.4%,
and the EUC values of other fresh mushrooms
would be 10-fold smaller. Because mushroom
mycelia are all freeze-dried or air-dried products,
their EUC were suitably calculated on the basis
of % dry matter.
THE EUC OF MYCELIA
As shown in Table 3, the EUC values of mycelia
also varied and ranged from the highest value of
460% (Termitomyces albuminosus) to the lowest
value of (Agaricus brasiliensis). ere are fi ve spe-
cies of mycelia at the second level, three species at
the third level, and one species at the fourth level.
Because of the small number of mycelia samples,
the EUC values of mycelia were not representative
of currently available mushrooms as compared to
those of fruit bodies.
e mycelia of Termitomyces albuminosus and
Morchella esculenta are the legend of the palatable
taste, and their EUC values of mycelia are consis-
tently higher than those of other mycelia, and even
higher than those of some fruit bodies. erefore, it
is of great interest to analyze the taste components
of their fruit bodies to fi nd out whether the EUC
values of fruit bodies are as high as those of mycelia
or not. Surprisingly, the EUC value of Grifola fron-
dosa mycelia (375%) was 30-fold higher than that
of its fruit bodies (12.7%). In addition, the EUC
value of Ganoderma tsugae mycelia was at the fi rst
level, higher than that of its fruit bodies. erefore,
it is benefi cial for its mycelia to be used in the for-
mulation of health food. In contrast, with respect
to Agaricus brasiliensis, Pleurotus citrinopileatus, and
Hypsizygus marmoreus, the EUC values of their fruit
bodies were higher.
For the rare fruit bodies of species such as
Cordyceps militaris and Antrodia camphorata, it is of
great interest for these mycelia with higher EUC
124 International Journal of Medicinal Mushrooms
J. L. MAU
values to be used in the formulation of health foods.
Because the mycelia of A. camphorata are better in
umami taste than its fruit bodies, the acceptability
and compliance of products could be improved. In
addition, our laboratory will focus on Volvariella
volvacea and Agaricus bisporus of the highest umami
taste, and use the fermentation process to obtain
their mycelia from submerged culture or solid me-
dium. e taste components of these mycelia will be
analyzed in order to understand whether the EUC
values of these two mycelia are at the fi rst level or
not. If so, these two mycelia will be an alternative
product to fruit bodies as foods or food-fl avoring
materials.
CONCLUSION
e umami taste is a kind of taste attribute remark-
ably diff erent from the traditional four tastes. e
addition of umami substances such as mushrooms
will change the taste characteristics of the food. Not
only the umami taste but also other sensory charac-
teristics such as continuity, mouth fullness, impact,
mildness, and thickness will be increased. Overall,
they increase the palatability of foods. e EUC val-
ues of commercially available mushroom fruit bodies
and mycelia summarized herein are valuable for their
further use as foods or food-fl avoring materials and
in the formulation of health foods.
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