“Discovery” of MSG … Dr. Kikunae Ikeda (1908) An attentive taster will find out something common in the complicated taste of asparagus, tomatoes, cheese and meat, which is quite peculiar and cannot be classed under any of the well defined four taste qualities, sweet, sour, salty and bitter. (Prof. K. Ikeda’s presentation at the 8th Int’l Congress Appl. Chem., Chicago, 1912)
“Discovery” of MSG …. An attentive taster will find out something common in the complicated taste of asparagus, tomatoes, cheese and meat, which is quite peculiar and cannot be classed under any of the well defined four taste qualities, sweet, sour, salty and bitter. - PowerPoint PPT Presentation
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“Discovery” of MSG …
Dr. Kikunae Ikeda(1908)
An attentive taster will find out something common in the complicated taste of asparagus, tomatoes, cheese and meat, which is quite peculiar and cannot be classed under any of the well defined four taste qualities, sweet, sour, salty and bitter.
(Prof. K. Ikeda’s presentation at the 8th Int’l Congress Appl. Chem., Chicago, 1912)
Basic taste categories
Sour
BitterSweet
Umami
Z
X
Y
Salty
Beef
Chicken
Yamaguchi, S. (1987)
Torii et al., In Umami: a basic taste, pp513-563 (1987)
Umami preferenceis a marker of
protein nutrition!
Preference for umami is related tolevels of dietary proteins
Umami (MSG)
Umami (MSG)
NaCl NaCl
NaClNaCl
Umami (MSG)
Umami (MSG)
Tomato’s full, rounded 'meaty' flavor comes from its heavy load of glutamates, and this flavor is reinforced by its unique crimson color.
0
20
40
60
80
100
120
140
160
180
Asp Ser Glu Gly Ala Val Met Ile Leu Tyr Phe Lys His Arg
Green
Pink
Red
Full ripe
(mg/1
00g)
Free glutamate in breast milk
0
2
4
6
8
10
12
14
16
18
20
TauAsp Thr Ser Gln Glu Gly Ala Val Cys Met Ile Leu Tyr Phe Orn Lys His Arg
(mg/100g) Total Glu intake = 0.393 g/kg/day!
“No MSG” labels …
• “While technically MSG is only one of several forms of free glutamate used in foods, consumers frequently perceive the term MSG to mean all free glutamate.
• For this reason, FDA considers foods whose labels say "No MSG" or "No Added MSG" to be misleading if the food contains ingredients that are sources of free glutamates, such as hydrolyzed protein.”
http://vm.cfsan.fda.gov/~lrd/msg.html
Glutamic acid metabolized during digestive absorption
Mouth
Glutamic acid from Food
Small intestines mucous membrane epithelial cell
Glutamic acid100% > 90%
Blood
Energy
Protein biosyntheses
Liver
Glutamic acid
Alanine,
Glutamine
Thermogenesis
Hepatic
portal vein
Liquid diet
171005
15
25
35
45
5
15
25
35
45
MSG (+)
Aff
eren
t N
erve
Res
pon
se
(sp
ikes
/sec
)
MSG (-)
Gastric Afferents of Vagus
5
Time (min)
An liquid diet without Glu, does not elicit chemoreception
Sensors for Glutamate exist on Tongue & Alimentary tract
Tongue (Taste buds) mGluR1
Small IntestinemGluR4 T1R1
Large Intestine mGluR4 &
T1R1
mGluR4
mGluR4 & T1R1
mGluR4
mGluR4 & T1R1
Stomach
mGluR1 & T1R1
T1R1mGluR1mGluR1
Intake of protein is recognized by umami receptors in the tongue and visceral receptors in the GI tract.
Increase of Gastric Afferent Activity
Amino Acid solution (150mmol/L, 2mL)
Glutamate-Sensing by the Gastric Vagus
SalineValLeu
IleLysTrpThrPheMet
GluGlyArgAlaProCysAspHisGlnAsnSerTyr
0 10 20 30 (, Spikes/sec)
AAs
Glutamate facilitated the gastric emptying of a protein-rich meal without influence on that of water or carbohydrate meal.
Free glutamate is an important substance for efficient protein digestion and absorption.
Gastroenterology (2006) 130(4), S2, A246,
Clinical Trial: Implications
Summary
The results clearly provide direct evidences of brain activation by post-oral stimuli with taste substances via either neural (vagal) or humoral signaling pathway.
Activated forebrain regions and signaling pathways
After infusion of taste substances in the stomach, several forebrain regions (cortex, basal ganglia, limbic system, and hypothalamus) were activated.
MSG-induced brain activation, but not glucose-induced one, was substantially reduced after vagotomy.