Taste and SensationTaste and Sensation(gustation)

Anatomy of Taste

papillae are not taste buds

Anatomy of TasteFour primary types of papillae:

• Vallate (or Circumvallate)- large, near back of tongue

• Foliate- on side of tongue

• Fungiform- larger, ‘mushroom’ shaped- “buds”

• Filiform- cover majority of tongue and

does not contain taste buds- used for mechanical grinding

Anatomy of Taste

Anatomy of Taste

taste buds (3)

papillae (plural)papilla (singular)

Fungiform papillae each have ~ 1-5 taste buds eachOthers can contain many more - up to 100 each

Each taste bud consists of 50 - 150 taste receptor cells

Taste buds are located within the papillae

Anatomy of Taste

neurons

Anatomy of Taste

Salt

Sour

Acidity - lactic, acetic and citric acid

Bitter

Probably developed as defense mechanism

and... Umami From the Japanese word ‘umami’ which means delicious

Na+Cl-

Sweet

5 basic qualities of taste (gustatory stimulation)

citric acid

Sweet and Umami

HO

O

NH2

O-Na+

O

monosodium glutamate

O

OOH

HO

HO

HO

HO OH

OOH OH

Sucrose (glucose & fructose)

nutritive sweetener

Saccharin (Sweet-N-Low)(300-500 x)

Sucralose (Splenda)(600 x)

SO2

NH

O

O

OOH

HO

Cl

HO

HO OH

OCl Cl

Aspartame (NutraSweet/Equal)(180-200 x)

Neotame(7000-13000)

NH

O OMeOH2N

HO2C

NH

O OMeOHN

HO2C

non-nutritive sweeteners

Umami:

N+ NH

ODenatonium

needs more work...

Bitter

Sour

citric acid

SaltyNa+ ions

flows into ion channels

causes polarization/depolarization within

cell and…

opens voltage dependent Ca2+

channel

increase in Ca2+ causes generation of

ATP (neurotransmitter)

SourH+ ions

flows into ion channels

H+ blocks a K+ channel

opens voltage dependent Ca2+

channel

H+ flow causes polarization/

depolarization within cell and…

increase in Ca2+ causes generation of

ATP (neurotransmitter)

SweetG-protein coupled

receptors (GPCRs)

cAMP transduction cascade

Blocks K+ channel

causes polarization/depolarization within

cell and…

opens voltage dependent Ca2+

channel

increase in Ca2+ causes generation of

ATP (neurotransmitter)

BitterG-protein coupled

receptors (GPCRs)

cAMP transduction cascade

CAN Block K+ channel

polarization/depolarization within

cell and…

opens voltage dependent Ca2+

channel

increase in Ca2+ causes generation of

ATP (neurotransmitter)

5th Cranial (Trigeminal) Nerve (Somatosensory System)

hot/coldtexture, mouthfeel, astringency

tingle/prickling

7th, 9th and 10th Cranial Nerves(Gustatory System)

5 basic qualities of taste

of the 12 pairs of cranial nerves...

Facial nerveTrigeminal nerve

Vagus nerve

Glossopharyngealnerve

5th Cranial (Trigeminal) Nerve (Somatosensory System)

hot/coldtexture, mouthfeel, astringency

tingle/prickling

7th, 9th and 10th Cranial Nerves(Gustatory System)

5 basic qualities of taste

of the 12 pairs of cranial nerves...

Facial nerveTrigeminal nerve

Vagus nerve

Glossopharyngealnerve

Somesthetic senses - responsible for chemical sensibility of the skin and mucus membranes.

• coolness of menthol• warming of chili peppers• tingle of carbonation

Tingle compounds

NH

O

NH

O

OH

enhances carbonation and alcoholic effect,cooling, warming and sweetness

refreshing or cleansing

Somatosensory system- made up of MANY nerves

hydroxy alpha sanshool

The sanshool chemicals, such as alpha-hydroxy-sanshool from the Japanese Sanchoo pepper and other Asian peppers, are particularly interesting because they not only give a hot sensation in the mouth cavity but also a tingling effect on the tongue

Tingle compounds

hydrophobic tail (lipid solubility)hydrophilic head (binding to receptor/nerve ending)

hydrophilic/hydrophobic balance required for trigeminal stimulation

{ {

NH

O

NH

O

OH

conjugated amide

NH

O

O

ONH

O

Synthetic Compounds

Cooling compounds

Mouthwash, body wash, shampoo, chewing gum, mints

OH

(+) menthol

OH

(-) isopulegol

Synthetic Compounds

O

O

OHO O

OOH

HNO O

NO

• hydrogen-bonding group• compact hydrocarbon skeleton• must have correct hydrophilic/hydrophobic balance

Pungent, Warming and Hot Irritants

pepper, chili pepper, ginger, mustard, horseradish, Wasabeact on thermal receptors

O

HO

NH

O

capsaicin(chili pepper)

N

O

Piperine(black pepper)

O

O

O

HO

O

zingerone(ginger)

O

HO

O

6-gingerone(ginger)

OHN C S

allyl isothiocyanate(mustard/horseradish/Wasabe)

Tannins - polyphenols

Astringency - irritate tactile receptors

Menthol

mintiness - olfactory stimulationirritation, cool/hot - somatosensory stimulationbitterness - gustatory stimulation

OH

All these add up to our perception of FLAVOR