RELATIVE TASTE POTENCY AND THE
COMPETITIVE OR COMPENSATORY
ACTlON OF SOME BASlC FOOD

CONSTITUENTS

Thesis for the Degree of M. S.
MICHIGAN STATE. COLLEGE

Herman B. Blum

1942

THESIS

30131: in taste Potency and
tho Comet itin or coupon-story Act ion of
Iona Basic l'ood Con-titan“

Ham 3. 311-

mlttod to tha Oradnato School of lumen
N. College of Lgicultm and Appnod
Scionco 1:: partial fulffllmnt of tho
requirunontu for the dome of
nm 01‘ some:

Mart-ant of Manley
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horned edgement

he writer wishes to express his sincere appreciation to
Dr. I. I. Mien. Research Professor of Bacteriolog. under
whose sue gum-ace this work we: done. for his never tailing
interest throqunt the course of the work and for his v
sssistsnce and criticisms during the preparation of this
Conscript.

he writer also wishes to express his appreciation to
I. ha [er-er. J. O. lundt, J. Zsrchin. D. lorse. 8. meters.
9. Gordon. I. Inner, G. Xorni’ield. 8. naaenbeua, I. nsnenbsun.
I. Youngrin. H. Birnbamn, I. 117015, I» Dara and 8. Dustin. all
fellow students. for their patient service as Judges in the

tssting work involved.

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lntrodnction.......................................
Literatm'e Review
Anatomy of taste..............................
Physiology of taeto...........................
Sense of snell................................
common chemical sense.........................
leseuring taste reactions.....................
felts thresholds..............................
Blending of f1srors...........................
lrperinentsl Procedure
Ehresholds of sensation.......................
competitive or compensatory sction............
Results
thresholds of sensation.......................
Discussion...............................
competition or compensation...................
Discussion...............................

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lntroduct ion

Parker (1922). who has and. the lost recent thorougi in-
vestigations into the field of taste reaction, believes that in
“ordinary food the flavor is a nixture of true tastes and odors
Moolpanied by the multitude of other huccal sensitivities due
to the variety of substances in the Iouth and accepted in a
rather Weed form by the central apparatus. Yet in all
this couplexity the elements rel-sin essentially distinct. 0on-
petition rather than cosponsation seems to be the rule'.

levsrtheless, Parker is forced to concede that there are
instances where gustatory compensation seems probable from
experimental evidentle offered but still mintains the doubt that
thq are true compensation.

It is not the Inn-pose of this paper to prove that cases
cited are true or false compensation but rather to work. with a
variety of basic food constituents to show their relative taste
potency and the effect they possess won one another. regardless
of whether the comensation is true or false.

he underlying purpose of the work is to show experimentally
how individul food constituents affect em' taste reactions.
either singular-11y or in combination with a contrasting flavor.

 

 

 

Eiterature Review
Anatosv of hate

he organs of taste. the so-called taste buds. were in-
dependently discovered by Levon and Schvalbo in 1876.

m (1890) found the distribution of the taste buds to
vary with the individml and age. In your; individu‘ls taste-buds
were found to be more widely distributed than in the adtflt. Later
stahr (1902) pointed out that the centsr of taste shifted with age
fro: a position near the tip of the tongm in the young to the area
of the vallate papillae in adults.

rucherlnsn (1889) and others have conclusively shown that
taste-buds when found. other than on the tongue. were embodod in
the opithelinn of the moons aenbraae. 0n the team. hovever.
they eero invariable associated eith a certain type of papillae
which have been desipated by their structure as conical. filiforl.
fungiforl and vallate. Of these. only the fungiforl. foliate. and
the vallate carry taste-bub.

It has been shown experimentally by fucker-Ian (1889) that the
lower surface of the tongue . the inner surfact of the cheeks. the
hard palate. and the uvula are insensitive to taste. to taste-
buds have been found in these regions. he mucous nsnbrsnes at
the beginning of the gullet. the region of the arytehoid cartilagos
within the larynx. the epiglottis. the soft palate and the tongu
are associated with taste sensations and in all these regions taste-

buds have been identified.

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i'he tongue of ash is his chief organ of taste and here there
is considerable difference between children and adults. A fucker-
In (1890) has shown that in children the entire 11er surface
of the tongue was associated with taste. shile in the adult taste
was confined to the tip. the lateral margins and the dorsal surface
of the root of the tongue.

According to Schiff (1867) and lost other workers in the field.
taste falls into four well defined groups. namely: saline. sweet,
sour. and bitter. rhese non clained that the great variety of
tastes associated with foods were a mixture of those for tastes.
However. there was not absolute accord on this since son classified
letallic and aniline tastes along the four basic tastes given
(Iahlaiborg (1898). and others).

cent-sen (1891) showed that distilled water is one of the veiy
few substances that excited no taste reactions. He attributed its
tastelessness to the absence of air. especially carbon dioxide.
since its insipidity disappeared upon aeration or even the addition
of carbon dioxide to the water.

According to Hanig (1901). the four basic taste reactions have
individual distributions on the tongue. (ass fig. 14) rho sour
sensation is beat down on the lateral edges of the tongue and is
accordingly associated with the folliate papillae and to scale extent
with the fungiforn papillae. rho bitter taste is largely located
at the base of the tongue nd is a function of the vallate millas.
lie saline taste is lost pronounced at the tip and lateral edges and

rig. h. Diagrams of the right half of the‘human tongue show—
ing the distribution of the four basic tastes.
(Iodified from Hanig. 1901)

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A.- the sour taste 3 - the saline taste

0 - the bitter taste D - the sweet taste

the sweet taste at the tip and lateral margin of the base of the
tongue. It would see. that the fungiforn papillae .r‘. largely
responsible for these taste reactions.

he distribution of the various taste reactions according to
neeow (18910 are shown in Table 1. His work demonstrated that the
reactions to sour. sweet. and saline solutions were exhibited almost
wherever taste-bus were found but to varying degrees. Accordingly,
the saline taste is lost pronounced at the tip. edges. base and in-
ferior portion of the tongue. his sour or acid taste reaction is
lost pronouced at the edge of the tongue while the sweet taste is
strongest at the tip of the tongue. growing weaker along the sides.

here was considerable agreement between Banig and Iiosow
except lanig apparently restricted the taste reactions to too

definite an area.

fable 1. Threshold values for individual papillae in different
parts of the taste field (after Iiesow).

Per cent conc. by weiglt

Gene

.3292. no}. 3359‘.
Tip of tongue . o . o . . . . . 0.25 0.0102 0.39
ldge of tongm (rt.). . . . . . 0.2” 0.0072 0.76
edge of tongue (1t. ). . . . . . 0.25 0.0063 0.72
Base of tongue. . . . . . . . . 0.28 0.016h 0.79
hft Palate . . . . . . . . . . 0.20 0.0150 1.50
Arch of palate (rt.). . . . . . 0.60 0.0100 1.50
Arch of palate (1t. ). . . . . . 0.50 0.0130 2.00
Urula............. 0.90 0.0200 2.50
Inferior tongue (rt.) . . . . . 0.30 mm 6.00
Inferior tongue (lt.) . . . . . 0.30 0.0500 5.00

Physiology of Taste

he dour i'asto:

he sour taste is excited by acids. acid salts. and materials
that produce acids. ‘11 these substances upon solution and sub-
sequent dissociation give rise to hydrogen ions. Richards (1898)
pointed out that all such solutions have a sour taste. and since
the one couponent they all have in col-non is hydrogen ions. it is
reasonable to assume that the sour taste is the result of the
bybogui ions. lahlenberg (1898) workingalong somewhat different
lines arrived at the same conclusion. a 0.0025 solar solution of
[61 has a lurked sou- taste. and a 0.0025 molar solution of IaGl
is tasteless. Both are considered completely dissociated and there-
fore the mlorine ions in both are equal. so Kahlenberg concluded
that the sour taste must be due to the hydrogen ions.

In work with organic acids. it has been shown by several workers v
that sou-noes of acids can not be solely attributed to the hydrogen
ion cementration. Richards (1898) working with tartaric. citric.
and acetic acids found then to be more sour than would be enacted
free their mdrogen ion concentration of their solutions. l'or ex-
uple. with hydrogen concentrations equal. acetic acid was approximately
five tines as sour as hydrochloric acid. lahlenberg (1898) estimated
that acetic acid was four times as sour as would be expected fro.
its hydrogen ion concontrat ion. Paul (1922) offered the following
data (fable 2) in proof that the hydrogen ion was not solely re-

sponsible for the sour taste.

Iable 2. dourness of acids. (Paul. 1922)

concentration of acids and hydrogen

Acids ions to produce equal sourness.
Acetic u. = 7 x 10‘” (a ) z 3 x 10'”
Lactic 23 x 10‘1‘ 5 x 10'“
mu 8 x 10'h h x 16'”
rarteric h x 10'” 3 x 10'"

Richards (1898) suggested that the sourness of organic acids
was due to the mdissociated ions acting as a reserve. producing
additional hydrogen ions as those present were used.

It is generally assured that to excite a taste. in puticular
a son' taste. the acid not penetrate somewhat into the interior
of the taste cell. Grosier (1916. 1918a and b) reasoned that if
this was the case. then the sour taste was due to the hydrogen
ion. but the intensity of that taste was dependent upon the speed
with diich the acid penetrated the taste cell. In work with the
penetration of acids. he gave the order of penetration to pl 5.6
in the tism of airomdnris as lactic acid. tartaric acid.
citric acid. and last acetic acid.

hlor (1927) in work with acid penetration into tissue
found that:

'1. Polar groups such as on. 01 and Br have a norm effect

in reducing the ability of acids to penetrate living
tissue.

2. Optical activity of the acids is important.

 

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be following charts and graphs prepared 1y ruler confirn
Orosisr's explanation of the action of acids on the sense of
taste. fable 3 showe that the external hydrogen ion concen-
tration can not be the only significant variable. figure 5
given the relative penetration of various acids.

table 3. hrsshold concentrations for the sour taste.
(”1915 1927 )

gig Geno. lorlal it 1)
l'oraic 0.0018 0.00055
Acetic 0.0028 0.00028
Lactic 0.0025 0. 00177
rat-taric 0.0022 0. 00010
Oxalic 0.0020 0.00116
hccinic 0.0032 0. 00031;
hutyric 0.0035 0.00027
Valerie 0.0037 0.00015

3. I. heatty ad L. 3. Greg; (1935) found that equi-sour
acids when titrated against a sediu dihydrcgen phosphate. di
sodiu hydrogen phosphate buffer syst- to a pa 1M5 used equal
amounts of buffer. Using a 0.0025! hydrochloric acid solution.
by testing. they determined the molarity of acetic. I110.
tartaric and chloroacetic acids that were equally sour. in...
were titrated against a buffer at p! 6.9 and the curves for each

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acid town in rigor. 6.

his was repeated varying the pl of the buffer and the
mlcity of the acids and wherever the curves crossed. they
found that the acids were equally sour. his curves consistently
crossed at a pH 11.45.

hey found that acids acre eosr than 0.001 I Hal can not
be conned by taste and titration measurements so their results
onlycowertherangeuptoasournessequel to that of0.01lhcl.

Iron their work over a variety of nolarities. they were
able to caph relative sourness of acids. (lie. 7)

hey used the phosphate buffer as given above at pl 6.9 and
titrated various strength acids to a pH M5. 'i'he titrations
were then expressed as eourness and graphed against nolar con-
csntratica.

Gregg (1937) noted that variations in the observed sourness
of acids could be attributed to variations in the pl of the saliva.
He found that the lore acid the saliva. the greater is the apparent
sournees of acetic acid and that there is sols mechani- ia add-
ition to buffering for resisting changes in the acidity of the
saliva.

he Nine Iaste:

he saline taste is typified by sodiu chloride but this is
not'ths only mound capable of exciting a saline taste. he
chlorides. bromides. and iodides of potassim and lithium as well

as their sulfates lid nitrates are acre or less saline in taste.

-11;-

Aqueous solutions of these salts are highly dissociated and
the results of work by [ahlenberg (1898) end lobar acid [issue (1898)
mowed the ions to be the stimulation agent. and in the case of
Iodine chloride. the anion was largely responsible for the saline
taste reaction.

Ishlenberg (1898) found that solutions of sodium chloride so
dilute as to be Just perceptibly saline were more dilute than a
solution of sodiu acetate equally saline in taste and hence con-
cluded that the saline taste lust be due to the chlorine anion.
ls flowed that equally dilute solutions of potaseim chloride
and lithiu chloride were eqmlly saline in taste as Iodine chloride.
thereby confirming that the intensity of the saline taste in these
solutions was due to the chloride ion. He also demonstrated by
similar tests that the order of effectiveness in exciting a saline
taste reaction was chlorine. bromine. and iodine.

crouor's (1931:) observations on the taste of salt solutions
showed colloids to be quite inactive in this respect. his work
showed that the saline taste sensation was predominately an effect
of crystalloids in true solutions.

the Bitter taste:

flat the. bitter taste was characteristic of almost all the
alkaloids. and certain other substances as the glucosides. picric
acid. other. and napesiun sulfate was demonstrated by Parker in
1922. lagiesiun sulfate. in cutrast to the sulfates of sodiu.

potassiun. ad lithiue which are saline. is bitter. and this

-15-

bitterness is attributed to the nsgnesim ion. Armenia md
calcium ions are also bitter in taste.

is town by Parker and aabler (1913). the nest effective
substances in exciting a bitter taste were the alkaloids as
mrphine. cocaine. quinine. nicotine. and strychnine. mesa
substances could be detected in great dilution. atrychnins
Ionoohloride. for example. could be detected in a solution con-
taining 0.0006 grams per liter of water.

Henry (1895) pointed out that bitter compounds often con-
tain the Nz-G-GHZOH coup. Other groups that midst be classed
as sapropheres were the amines. hydroxly. and nore than one 102
grew in a cospound.

litter taste was shown by Herlitzlra (1909) to be associated
with the cation with the exception of picric acid. where it was

the anion.

he fleet lasts:

According to Parker and Stabler (1913) the sweet. more so
than the bitter taste. was caused by organic compounds and centered
about the alcohols and the sugars. the majority of which sere the
aliphatic alcohols. Gertain other carbohydrates and a few organic
salts excited a sweet taste. Among the inorganic salts. lead
acetate was lost comnly considered sweet.

be question of what causes the sweet taste is far Ira
settled. the comon hexose sugars found in nature differ cen-

sidersbly in their degree of sweetness and yet they are isomers

-16..

of each other. Oohn (19131) concluded from his work that sweet.
tasting substances contained certain structural groups that
determined their taste. as with alcohols. one hydroxy group was
associated with a sweet taste and four or five hydroxy groups
were accolpmied with a considerably stronger sweetness in taste.
Gertly and layers (1919) proposed quite an elaborate determination
for the constitution of the sweet taste. assuming that at least
two maps were present in each sweet molecule. a gluosphore and
an auoglnc. .

may defined a glucophore as 'a group which has the power of
forming sweet compounds by uniting with a umber of otherwise
tasteless stone or radicals. and an auxoglnc as 'an atom or radical
which combined with any of the glucophoree yields a sweet con-
pound'. hey listed six glucophores and nine auneglucs. Ihs
glucophores and an example of a sweet coupound formed is given in
fable 3. he auxoglucs are given in Mle 5. I

Bruce (1929) has nade some interesting observations on the
chemical constittnion of taste and in particular on the sweet
taste. He found that extremely dilute sedim- and potassium
hydroxide solutions tasted sweet. He stated that glycols and
sugars were sweet but that the sweetness did not increase with
the nmber of hydroxyl mops. his is contrary to the work of
Gohn.

Druce in his work with sweet and bitter substances observed

thd in homologous series of organic compounds. bitterness in-

 

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-17-

creases and sweetness decreases with rising molecular weight.
He also found that in em cospounds the meta form is sweet. but
the orthe and para cospomds are bitter. This has been confirmed

by others.

Eable it. he glucophores. (Oertly and layers. 1919)

Glucophore hample of a sweet compound formed
2. ~00-OEOH glycolaldehyde
3e m.m2. um"
h. menace ethyl nitrate
5.e -x _ H --x CEBr-
ch 0.2, “an
,e a -
6 ‘33: ”a“

"' ll - halogens
x - umber of halogens

fable 5. he aunoglucs. (Oertly and layers. 1919)

1 . n- 5. (m3 )2-cs

2 e fl3-Q2- 6e 032“

3. “3- 7. GB-GHOH

It. cs3-csz-ss2- 8. mews-cae-

9. Radical 0n Ian 1 0n of aerial polyhydric alcohols.

l'insi. 0. and Oolonna. I. (1938) in their work on the cheeioal
constitution of sweet taste found the theory of Oertly and layers an
inadeqmte explanation. hey cited n'aserous examples of substances
that do not follow the plan of 0ertly and layers.

-18..

House of atoll

no sense of well is man is the result of nasal stimulation.
According to Parker (1922) this stimulation falls into two classes
of substances. irritants and true odors. he irritants effect the
trigeminal terminals which are a part of the cannon chemical
sense referred to later in this paper. whereas. the true odors
stimulate the olfactory nerve endings. Parker'contends that they
are not entirely separate since certain substances act to stimulate
both types of nerves.

"chow and Kerpmen (1917) found that the time needed for an
olfactory susatien to disappear was directly proportional to the
surface tension of the odorous material. his and other ob-
servations lead to the conclusion that olfactory stimulation was
the result of material particles.

In testing olfactory acuity the majority of workers have
used the method of evaporating a known weight of substance in a
hen values of air. Using this method. l'ischer and Pensoldt
(1886) working with chlorophenol and mercaptan. derived some
outstanding results. Por example. 1/230.ooo.ooo ump- of
ohlorerhenol per cubic centimeter of air was found to be suf-
ficient concentration to give an olfactory sensation. Iercaptan.
a substance giving a garlic odor. caused olfactory stimulation in
a concentration of 1/23.000.000.000 milligram per cubic centimeter.

Pasq (1892) has made similar minim determinations for a

number of substances. some of which are given in table 6. It

 

 

may be noted that there is some disagreement among various sets
of data in minim determinations for the sense of smell. but

they all emphasise the sentences of man's olfactory sense.

Eable 6. linimum concentration for olfaction in thousandths of
a milligram of substance per liter of air. (Pansy. 1892)

stance thousandth. of a minim
ltlul ether 1.0
citral 0.50 to 0.10
Orrin 0.50 to 0.01
Millin 0.005 to 0.0005
lethyl alcohol 10.0
ltwl alcohol 2.5

var... (1903) found that upon introduction of a solution of
an odorous substance into the nasal cavity. an olfactory stimulation
resulted. but the sensation was not that of the original substance.
it has been established by Blackman (1917) and others that vapors
of odorous substances. before they can cause an olfactory stiIa-
latien. must go into solution with the watery mom and in this
state cone in contact with the olfactory hairs. Blacknan has
firther town that before the substance can gain entrance into ,
the hairs it must also be soluble in the oily coating of the hairs.

It is well known that olfactory organs are quickly fatigued
by continmus exposure to an odorous material. Persons working
along disagreeable odors soon become insensitive to these odors.
Aronsohn (188M attapted to determine the time necessary for

-20“,

olfactory fatigue. Oil or lemon and oil or orange were smelled
by nine persons until thq could no longer distinguish these
odors. ls fomd that it took from 2.5 to 11 minutes with an
average of 3 minutes for obliteration of these odors. Recovery
was found to be equally rapid. being fun 1 to 3 minutes.

Ano-ia. a condition in which persons are absolutely devoid
of true olfaction. was shown by Glaser (1918) to exist. fliers
can also be partial temporary anemia.

leaning (1916). in working with the quality of odors. has
produced the olfactory primn. (rig. 8) lith it .he has tried to
files the relationship between his six basic odors which are as
follows:

1. Qicey odor. as those of fennel and cloves.
2. flowery odors. such as those of cmarin.
3. fruity odors. as those of orange.

h. Besinous odors from turpentine.

5. Burnt odors. such as those from pyridine.
6. real odors likn hydrogen sulfide.

Between these basic odors. all intermediate odors new be
imagined to fall somewhere on an edge or on the surface of the
prin. filis was the relationship Henning believes to exist
between various odors. whether basic or intermediate.

It is readily adnitted that olfaction is essentially a
fluioal process and little progress has been made to dlow the

relation between chemical structm'e and olfaction. Pansy (1892)

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set w the following table (fable 7) to files the relationship

between various alcohols and their relative olfactory potency.

Pig. 8. leaning's olfactory prism.

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(Kenning. 1916)

fable 7- towing olfactory potency of alcohols. (Pastor. 1892)

£52132; Relative Pot ens:
[ethyl 1.0
lthyl h

Prowl 100

Dutyl 1000

Ml 10M

toning has done a great deal of work with aroaatic coqoulds
and null and has concluded that various smells were not a result
of the oemophoric groups (hydroxyl. aldehyde. htene. ester. sitro.
and nitril groups). but rather the result of the position they
occupied on the benzene ring. has in the flowery odors the
o-ophoric coups were is the meta or srtho positions; in the fruity

-22“

odors the peeps were forked: in the resinous odors the groups were
within the ring: in the burnt odors the ring was smooth: and in
the foul odors the ring was nagmentary. Intermediate odors were
due to the combinations of the groupings.

drensohn (1886). in working with combinations of odors.
arrived at a number of interesting conclusions. In odors well
balanced will appear as a single odor different from either of
the original odors. If the odor is not well balanced. the stronger
will dominate.

rho demon musical Bones

It has long been known that in the nasal cavity of man there
are two types of nerve terminations: the olfactory nerves for
our true sense of men. and fr» nerve terminations which are
stimulated by irritants and whose system is part of the semen
chnical sense.

Guglill (1911‘) has produced evidence that indicates that
these receptors were in reality a part of our tactile sense. how-
ever. as rerker (1922) pointed out. this is not definitely es— '
tablished dnce there is also evidence that indicates our semen
chemical sense is a separate vetem of nerves.

file colleen clinical sense has little i: do with either the
sense of taste or the sense of smell. Parker and Stabler (1913)
have diewn that the minim concentration of etlwl alcohol
necessary to stimulate man's irritant receptors is five to ten min

which is considerably stronger than will stimulate man's gustatory

organs (about three molar) or olfactory organs (about 0.0001
molar).

leasuring recto Reactions
lethodst

be methods of measuring taste reactions are naturally varied.
depending upon the purpose and the investigator. lore we shall
only be concerned with the studies on taste thresholds. placements.
ad cenpasatien. l'er sable of clarity. the processes for measuring
taste reactions are reviewed by taking certain variables inde-
pendently and comparing the investigators' methods.

Richter and Man (1939) in their studies into salt taste
thrediolds attempted to evaluate four methods. In the firet
aethod tried. they placed three drops of solution on the subject 's
tongue. boy found this method poor due to the difficulty in
placing exactly three drops on the tongue and the great dilution
of the all quanity of stimulus by the saliva of the month. In
the next two nthods the subjects were given 10 ml. of solution
in glass containers. but in the first of these two methods there
was no distilled water given between samples. while in the other.
a distilled water wash was given the subjects between each sample.
In the forth method used the subjects were given two containers.
one with the solution being tested. the other with distilled water.
he subjects were allowed to sample both until satisfied with the
taste.

be second method was fond inadequate because the subjects

-214-

were givui no distilled water between samples for a comparison
and as a result it was difficult to state when a change occurred
in the increasing salt concentration.

lhe next method. with distilled water between each sample.
was chosen by the investigators as the most adequate. he dif-
ficulty here was that the subJects did not have sufficient
opportunity to compare taste of the two liquids.

i'o off-set the difficulty in the previous method. the fourth
method was used and found adequate for some work. has difficulty
here was pqdiolegical and as would be expected. the threshold
values were lowest by this method.

front ad fliarp (1937) used a method very similar to the
fourth method of Richter and lacLean. Approximately 75 ml. of
solution~ in 100 ml. beelners was used for placement work. he
Judges were allowed to taste as large a sample as desired and were
also allowed as many retastings as thqy thought necessary. h
voltme moments and the amber of trials. the authors deter-
mined the average voluse per tasting. i'we Judges. making 190
tastings. averaged 6.13 ml. per tasting.

A. Beister. s. Ieigley and c. s. Iahlin (1925) made a study
of the relative sweetness of pure sugars. heir method consisted
of a 1.5 ml. distilled water rinse. removing the moisture from the
tip of the tongue with a cotton swab and then “placing one drop of
the solution on the Judge's tongue. Results were recorded as sweet
or not sweet.

rouleuse and Veschids (1900). in their work on measuring taste

reactions. used 1 ml. of solution placed upon the protruied tongue.
Camerer (1869) used 10 ml. of stimulus in an ordinary drinking glass.
In some of his studies. Gamerer used as much as 30 ml. of solution
per tasting. lahlenberg (1898) gave his Judges h ml. of solution
hem a porcelain spoon. Richards (1898). in working with acid
solutions alone. allowed the Judges to take small mouthfulls of
solution Hem an ordinary drinking glass. Snore (1892). in deten-
mining comensatien in testing, used two drops of solution placed

on the tongue. King (1937) found 5 ml. portions given in small
beahd'e adequate.

romperature coefficient:

i'he effect of tanperattu-e on the taste of sapid solutions is
another variable in methods for determining taste reactions.
lollingworth and Peffenberger (1917) were of the opinion that
thermal stimuli had a considerable influence upon, the effect of
taste stimuli. he, also stated that the optimsl temperature
varies from 55° 1'. to 120° 1‘. At the optimal temperature the
least amount of empid material is necessary to arouse a taste re-
action. Au deviation in either direction will cause an increase
in the qunity of sapid material necessary to arouse an equally
intensive reacton.

Iiesew (1891!). on the other hand. believes that the teger-
ature of sapid material has no effect on the taste reaction. but
does maintain that the teuperattu-e of the mouth previous to testing

has a marked effect on the taste reaction. ler example. he holds

that tasting is equally acute at 32° 1'. and 100° 1'. [hen the
temperature rises or falls beyond a certain point. the temper-
ature reaction becomes so strong that the taste reaction drops

out of consciousness. In his experiments. Kisses used temperatures
of 10° 0. to 20° 0.

Partner (1922) points out that the stimulation of the taste
receptors is probably a chemical process and as such there should
be considerable temperature coefficimit. He goes further to state
that as far as he is um no studies have been carried out with
this point in vies.

lemurs (1921) found a goat temperature coefficient between
10° 6. and 20° 0.. having the sensitiveness of reaction increase
100 per cent in this increase in tenperature. He also found the
reverse to exist between 30° 9. and 140° 0. from this. the optin-
temerature for taste sensitivity is between 20° 0. no, 30° 0.

Ousror (1869) studied salt solutions at 5°. 10°. 20°. 30°.
h0°. 50°. and 60° 0. and found the optim range betseem 20° and

30° 0.
larohmnd (1903) believed that optimi- temperature range
is between 30° and 110° c. and cited experiments which showed
that in 0rd: to get the same intensity of reaction from sapid
material at 0° c. as at 30° 0. Ron four to thirty times as
Inch sapid substance must be used. Iarchand offered the following

.IPOrimentad data. (name a)

 

I. uglftni ..,- 4...; . a

G.

-27“

fable 8. lffect of temperature upon threshold values. (Iarchand.

 

1903)
substance hrsshold values given in parts per 100 at
30° to W 0, at 00 0.
sugar 0.10 0A0
blt 0.05 0.25
citric Acid 0.0025 0.0030
Quinine 0.0001 0.0030

a. bent and P. Slurp (1937) concluded that maximtls dis-
criminatory ability for mspective solutions was as follows:
sodiun chloride. 21° 0.: sucrose. 350 6.: lactose. 35° 0.:
lactic acid. 21° 0.; quinine sulfate. 21° C.

lichter and Campbell (1939) found no correlation between
teqerature of solutions of sugar and threshold values when 10 m1.
portions were taken into the mouth.

fins Interval Between test ing:

News: (1911‘) believed that tasting in rapid succession had
no effect on sensory acuity. but did effect subsequent Judgments.
l'or ample. in studies with salt solutions. if the solution
that was being tasted was weaker than the preceding. there was
a tendency to call it salt. whereas. if the solution being tasted
was stronger than the preceding one there was an equal tendency
to call it water. Brown allowed an average of 25 seconds for each
solution.

Gamerer (1885) permitted a pause ranging from two to five
minted between samples. tile King (1937) specified a pause of

two minutes between samples. The time the solution rained in
the muth was not specified.

rreut and Slurp (1937). and Richter and seetean (1939). in
their studies. Me no time specifications. allowing the subjects

to proceed as rapidly as desired.

Reaction i'ime to Stimuli:

he reaction time or latent period for taste excitation is
the time interval between application of the solution and appear-
anoe of the sensation. (Grosier. 193%)

[loans (1903) determined the reaction time for four different
solutions. and showed that this time was greatoat for bitter. next
smaller for acids. next for sugars and least for salt solutions.
He gave the reaction times as follows:

Salt . . . . . . 0.308 seconds
Sugar . . . . . . GANG "
icid......0.536 '
Quinine.....1.082 "

lollingworth and Poffinbergsr (1917) studied the effect of
tonperature upon the reaction time. Lowering the tmnperature of
the solution below that of the mouth did not affect the react ion
tin for salt. but lengthened the time for other basic tastes.
Raising the temperature above that of the mouth decreased the
reaction time to neat. but increased the reaction time to bitter

Ind ”We

taste of Iater:

Parker (1922) stated that insipidity. such as was character-
istic of distilled water, was probably real tastelessness. King
(1937) pointed out that the Judges noted tastes for distilled
water and agreed with Crocher and Henderson (1932) that it took
several days of tasting before the Judges became accustomed to
the tastelessness of water. Gradually a reaction was built up
where water really appeared tasteless.

he most common reaction to water. as found by Titdiner
(1901) and Brown (191%). was that of bitter. described as a
smooth bitter.

Kahlenberg (1898) oomnented on the tastelessness of water.
He pointed out that since taste was probably a chemical reaction
and that distilled water was composed of undissocisted molecules.
then distilled water was really tasteless since no chemical re—

action was possible.

Other Variables:

more are a few other variables that enter into methods of
steaming taste react ions. King (1937) found no relationship to
exist between acuity of taste and age or smokers. Blekeslee and
Sol-on (1931) concluded that females were somewhat more acute
tasters than males. Boclike and Routh (1932) found that non-
smokers could taste weaher concentrations of common acids.

Richter lid Campbell (1939) concluded that the following

conditions were not fomd to affect taste sensitivity for sucrose:

-30..

chronic alcoholism. excessive smoking. badly infected gums.
marked decay of teeth. mild head cold. and hay fever or allergy.

faste Threaholds

A great number of studies have been made to determine the
taste threshold of a variety of substances. but they are of
little cosporative value since there is no uniformity of method.
ihis lack of uniformity in method is largely due to a lack of
standard definition of the threshold of taste. richner (1905)
regarded the threshold. or linen value as that magnitude of
stimulus which Just brings a sensation to consciousness. Brown
(19151) believed it to be at some point on a scale mid-way between
the intensity which is Just barely strong enougi to produce a
sensation and the intensity which always produces a sensation.

Richter and Campbell (1939) need possibly the most definite
method. hey believed that the gustatory threshold disuld be
divided into two individual thresholds. a difference threshold.
and a taste threshold. he difference threshold represented the
point were the subjects could.) differentiate between a sapid
solution and distilled water. while the taste threshold was the
minim concentration which the subject could recognise.

King (1937) set up score csrds whereby she could dbtermins
the so-called 'difference threshold' and the “taste threshold“.
but recorded her data only as thresholds and offered no emissi-

ation as to the means used to arrive at this threshold.

-31..

Parker (1922) in his extensive study into the sense of taste
selected the following as being representative threshold values:
Per cent
Sucrose....... ......... .. 0.685
bdrochloric acid........ 0.009
Sodium chloride. . . . . . . . . . 0.231!»

Quinine twdrochloride. .. . 0.0016

[morons workers in the field of taste reactions have
att-pted to determine the threshold values for various sub-
stances. i'ehle 9 gives new of these figures for the four
basic taste reactions. All the figures have been converted
to percentage. he great variation in results may be attribu-
ted te variations in methods and to the individual definition
of thremold of taste.

In working with sugars. many have concerned themselves only
with relative taste although in new cases these weredetermined
by the relationship of threshold values. Table 10 gives the
relative values of the sweetness of the more comes sugars as
found by their respective authors. Here again there is con-
siderable variation. especially for the values assigned to in-
vert sugar. and this may largely be attributed to the mistions

in “md'e

 

y‘

Itvys‘h
VH?‘ LEW- A'Ils ej

-32-

lable 9. Frequently quoted threshold values representing the
four basic taste reactions.

Substance

author

but. Chloride

bdrechloric

Blabslee and Solomon (1931)
Crocker and Henderson (1932)
King (1937)

Yenables (1887)

Bailey and lichols (1888)
Znnts (1891)

liesov (189M)

Hanig (1901)

Barley and Dean (1936)

Grower and Henderson (1932)
line (1937)

Venables (1887)

Bailey and lichols (1888)
Banig (1901)

Blekeslee and doll-on (1935)
Richter and canpbell (1939 )

acid

Yenables (1887)

Butt: and Grace (1935)
Kenning (1916)

Blahslee and some (1931)
Iiesow (1899)

Bailey and lichols (1889)
Blekeslee and alien (1931)

hreshold in
percentage

0.31:
0.17
0.11
0.10

0.05
0.10

0.3
0.

0.19

0.72
0. 57
0.30
0.50
0-35
1.28

0.55

0.010
0.036
0.019
0. am
0. 010

0.”)
0.0032

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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-31.-

from this and other work there arises a very interesting
correlation between acuity of taste and reaction time to the
four basic taste reaction substances. This correlation holds
generally for other substances classed in the four basic taste
groups. Bitter tasting substances as a rule show taste re-
actions in the greatest dilution and also have the longest rs-
aotion tine. Acid solutions are next in acuity and their
reaction tins is second longest. Sager solutions follow next
in this order and salt last with the highest threshold values
and the diortost reactions tine. 1311s is odd indeed since it
would logically seem the reverse of this order.

Rent and harp (1937) found the sense of taste capable of
discrimination changes as low as one per cent sodius chloride
solutions ranging in concentration from 0.13 to 0.20 per cent.
'ith sucrose. lactose and lactic acid solutions, ten per cent
changes in concentration were readily detected. may also found
that snout of substance required to produce a noticeable change
in sensation was only a haction of the usually stated thrediold
value.

Blending of flavors
Parker (1922) believes that in all complexity or taste nin-
tures the elements remain essentially distinct. concluding that
eospetition rather than-couponsation is the rule.
Iieeow (1891‘) studied sucrose and sodiun chloride aintm‘es
and diowed the effect of small amounts of salt in neutralising

the sweet taste of sucrose. At alconcentration of one per cent
the ratie of sugar and salt to bring about neutrality was found
to be 0.5 to 0.25 respectively: while at a concentration of ten
per cent. the ratio for neutralising the sugar was about 0.5

to 0.03 respectively.

tom and Lamar (1940) have shown that acetic. tartaric
and citric acids when added to sucrose solutions show a de-
crease in acid taste. They concluded that the degree of
acidity is dependent upon the concentration of the sugar sol-
ution.

i'itchener (1931) also points out the contrast of sweet and
sour and adds that bitter does not contrast with any other taste
and so can mt be eliminated by cosmsnsation.

ths (1892) found that a one per cent solution of sodius
chloride increased the sweetness of sugar solutions. Hegel (1896)
Med that a sleuth wash of potassium chloride sands distilled
water taste sweet, and Lance and loose (1888) fond that after
the tongue was held in dilute sulfm'ic acid for a few minutes.
distilled water and even quinine were capable of exciting a
sweet taste.

Gregg (1937b) using the method of Beatty and Gregg (1937)
attempted to determine the effect of salt and sugar upon scurness.
his results indicate that the addition of three per cent sugar
decreased the sourness of hydrochloric acid 15 per cent by taste
and no per cent by titration against a buffer. He also found

-35-

that the addition of sodium chloride does not affect the sour-

ness of acids.

Muted Procedure
mesho Ids of Sensation

fifteen Judges were availagle througiout this part of the
work. the experiments started with 25 Judges but ten were
elininated for various reasons. such as. carelessness in tasting.
inconsistency. and very limited availability. All the Julges
were students with very limited or no previous tasting experience.

he tasting was done from 100 ml. backers. each containing
five nillileters of solution pipetted for the Judges by the
author. Iith each substance. a Judge uas given a direction-
data sheet (lo. 1). The author remained with the Judges while
tasting to insure uniform procedure.

rho Judges were allowed only one tasting of each solution.
Bach Judge tasted each such substance twice. at different sittings
so that each threshold value represents at least 30 Judgings.

i'he tasting work was done on basic food constituents. How-
ever. calcium chloride. alminun chloride, and stannic diloride
were used to determine the effect of the onion in salts upon taste
by varying the cation: using mono. di. tri. and tetravalent cations.
ratio 11 gives the substances used and their respective consent
trations.

In noting solutions of these substances certain precautions

were observed. All glassware was thoroughly cleaned with cleaning

’ .—.‘ '..— ,‘-| T 4 ' 1
air'!'uuLJ-l—Juvu -. J lb “Os

RESEARCH ON FLAVOR

Name of Judge Substance Date Time

Procedure: Rinse the mouth thoroughly with distilled water. discarding the
water. Four 5 c.c. of Solution No. l in a beaker. and then put
it in your mouth. Swish the solution around so that it reaches

the back part of the tongue. Discard. Record the taste. Rinse
the mouth with distilled water again. Wait two minutes then taste

Solution No. 2. Use a clean beaker for each solution. Continue
through the series with the same procedure.

Insert number designating the intensity of taste of the numbered solu-
tions. using following key:

0--No taste
1~Very faint
2wFaint
Easily noticeable
Strong

5~Very strong

W i W
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Intensity.................... i

 

 

 

 

 

 

 

 

 

 

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What was the taste?

1lumber of solution at which taste was first identified

 

How long since smoking before taking the test?

81w long since eating before taking the test?

 

 

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511;;-

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solution (32%“20r207h well rinsed with tap water and finally

rinsed with distilled water.

1‘01. 11 e

Bolts:

hear-t

Acids:

Ioler concentration of substances used in determining
the thresholds of sensation.

Sub at once

mdium chloride
calcium chloride
llminum chloride

Stunnic chloride

Sucrose

Dextrose
fructose
Lactose 0.050

laltoso

Acetic acid
bdrochloric acid
Citric acid
Ialic acid

Lactic acid

7 Generic acid

0.005
0.005

0. 00025
0.00005

0.0075
0.025
0.010
0.075
0.010

0.0005
0.0001
0.0001
0.0001
0.0001
0.0001

£0351; ggcentrgggg
O. 010 O. 025 0. 050
0. 0075 0. 01 0. 025
0.005 0.00075 0.001
0. 0001 0.00025 0. 0005
0. 010 0.025 0. 050
0.050 0.075 0.10
0.025 0. 050 0. 075
0.10 0.125 0.150
0. 025 0. $0 0.100
0. 00075 0. 0001 0. 0025
0. 00025 0. 0005 0. 00075
0.00025 0. 0005 0.00075
0.00025 0.0005 0.0075
0.00025 0. 0005 0.00075
0. 00025 0. 0005 0. 00075

 

0.070
0.050
0.0025
0.00075

0.075
0.125
0.100
0.175
0.100

0. 0030
0. 0010
0. 0010
0. 0010
0. MO
0. 0010

for each substance listed in Table 11. a standard was accurately

lode and in the case of the salts and acids checked by titration

Casket known standards.

It was from these standards that solutions

h t I
. 1 .
O ‘ D
. a T
v ¢ I

. -IIEEOE

 

 

-39..

tasted were made by dilution using has pipettes and volumetric
flasks. For the sugars. no checks were made but samples were
accurately made by weight and dilution. All solutions were sleds
with fresh distilled water from a Bernstead still.

All substances used were 0.P. chemicals from established
clinical supply houses. ‘l'ney were made Just prior to use and
allowed to stand for no longer than a few days. The tasting work
on one set was completed by all tasters from the some solutions.

In recording the data. the first solution in the series of
increasing concentrat ion that differed from the distilled water
in taste was the sensitivity threshold whereas the first solution

in which the taste could be described was the taste threshold.

Correlation between Buffer and burns“
following the pattern of the work of Beatty end Gregg (1935)
attempts were made to correlate sournese with titratione against
a lisosphate buffer.
A buffer was ads as follows:

3.21l gas. “30“ ' £20
20 cc. of approximately 1! non

ends a to one liter - final pH 7.05
A variety of solutions of each acid was made in the same manner
as previously described. Using 10 ml. of the buffer solution
diluted one to five, acid was added until the p! on the Bechsn

-eter reached #36. At this point. according to Beatty and Gregg.

acids using equal amounts are equally sour. The amount of acid
necessary to bring the pH to this point was recorded.

i'en molar solutions of each acid were thus titrated and the
milliliters of each titration plotted (Figs. 10 and 11) to de-
termine relative sourness. ibis was done in two sets of solu-

tions so that appropriate dilutions of the buffer could be used.

competitive or compensatory Action

2o determine if one substance acted in a competitive way with
a contrasting substance or in a compensatory say. two methods 1
were need.

he first method consisted of testing a series of five solu-
tions and comparing them to a control (Tables 19 to 22). l'or
this work. a series of six solutions was made of equal concen-
tration of a substance. all above the taste threshold. he first
was designated as the control and to the remaining five was added
a contrasting sub stance in increasing concentration ranging
between the sensitivity and the taste threshold.

This method was used on a series of four combinations of
acid. salt and sugar and because of rather inconsistent results.
it was discarded in favor of the second method. Ihe direction-
data sheet (lo. 2) for this work is found on page in. However.
some information was derived from this method and it lead to
the use of the second method. light Judges were used for this
work.

be second method consisted in matching molar solutions

~ .1 4 v1 .Ft‘t.‘ I , l n ‘
a.. «vial; .1“le win.-- o-se no

Research on Flavor

Name of Judge - ; Iories N0. mte' Time

Procedure 3

Rinse the mouth thoroggglz with distilled water, discarding the
water. Place s0 ution 0. l in your mouth, swish about so that
it reaches the back part of your tongue. Discard. Record the
taste. Again rinse the mouth thoroughly with distilled water,
discard and after waiting about one minute taste solution H0. 2.

continue in the same manner throughout the entire seriesJ
RECORD TASTE AFTER EACHfiSOIUTIONJ

Use solution No. l as a guide and record solution N0. 2 as stronger
or weaker according to the key below. Also record the taste; 1.6.

salty, bitter. sweet. etc. solution No. 1 should be tested before

each of the other solutions.

'2 an]. 0 +1 +2 +3

 

-3
‘ much noticeably slightly Same slightly noticeably much
weaker weaker weaker stronger stronger stronger
Solution gt. Change 33 tests Taste
__ l . __ Control

 

 

 

 

 

0‘me

 

 

 

 

 

-142-

where the solution to be matched contained a greater than the
taste threshold concentration of a substance and in addition a
sub-taste threshold concentration but geater than sensitivity
threshold concentration of a contrasting substance. This
solution was matched to a series of five solutions of increasing
concentration of the greater than taste threshold substance.
i'he series of solutions was made with sufficient difference in
concentration so that the Judges could easily not ice the increase
in taste and the concentrations usually varied above and below
that of the solution to be matched. l‘or example. a moderately
strong tasting solution of sucrose to which had been added a sub-
taste thrediold amount of sodium chloride was matched to a series
of solutions containing only sucrose whose concentration varied
above and below that of the control solution. 'l'he same method
was followed with the other sugars and acids (Table 23).

Competition or couponsation was determined by the Judges'
choice of solution. If the substance added showed a compensatory
action, it was indicated by the Judges' choice of a solution
other than the one of eqml concentration of the substance tasted.
If. a: the other hand, the choice of the Judges was a solution
of soul concentration of the substance tasted. competition was
indicated since the sub-taste threshold substance did not add
or detract from the taste of the solution.

his method proved very satisfactory in determining the effect

of sub-taste threshold concentrations of one substance upon mildly

 

-15-

strong tasting concentrations of a contrasting substance.

Using this method, experiments were made to determine the
effect of sodius chloride on all the acids and sugars listed in
fable 11. he effect of each individual acid on dextrose. suc-
rose. fructose and sodium chloride as well as the effect of all
the sugars on all the acids was determined. This made a total
of 6” such determinations to cover this work. (Tables 23 to 35)

Iimilar precautions were followed in these determinations
as in the determinations of the threshold of sensation in re-
lation to the making of the solutions.

For the tasting work 100 ml. beakers were used and the judges
were given as much solution as needed. There was no control on
the amount of solution tasted, the time for tasting, or the number
of retastings. me Judges were allowed as much solution as desired
and as my retastings as they found necessary to satisfactorily
choose a matched solution.

It was found adviseable to have the Judges compare solutions
one. three and five with the unknown to determine the relationdiip
and then attmpt to match the unknown with a single solution by
elimination. Thq were told that the series was in order of in-
creasing concentration.

lash set of solutions was tested by ten Judges although there
were fifteen available for the work. ‘lhis was done because some
Judges were either very sensitive to sugars or acids even thong:

these were added in sub-taste threshold concentration, they so

 

altered the taste for some of the judges that matching was im-
possible. It was always found that the ten chosen could make

what they felt were honest matchings. Between each set of matchings,
the Judges were required to wait about two minutes. Part of this
time was spent in thorougily rinsing the mouth free of the pre-
ceding solution.

As a rule. sour solutions were left for the last. It was
found that when they were tested first they so sensitised the
muth that if the following series contained acids in sub-taste
threshold concentrations. the acids were tasted and in some cases
to each an extent that the taste of the pester-than-taste-thres-
hold-substance was almost conmletely obliterated.

It was also found that the Judges could not do lore than one
series of acids at one time. Beyond this. they could not distinguish
between the solutions of increasing concentration sufficiently to
do satisfactory matchings. In making the sour solutions. care had
to be exercised to insure that the solutions were sufficiently
strong so that they could easily be tested by all but not so strong
as to be irritating to the delicate membranes of the mouth. Judges
were able to taste with accuracy an average of three sets of solu-
tions at one time with the usual two minute rest between sets of

solutions.

correlation between Buffer Titration and deepeneation

In the case of aside, an attempt was made to measure the change \

in sourness of acids. upon the addition of Incl ud sugars. by
titrating with the phosphate buffer. This was done to determine
if a relationship existed between changes in taste and buffer
titration. hr this purpose, the buffer was made up in the same
manner as before and then diluted 1:25. To 20 ml. of the acid.
buffer was added until the solution reached a pH ”.115. me amount
of bfifer necessary for this was recorded. ibis was repeated with
acids to which had been added sugars or sodium diloride in the same
concentration as for the previous determination. he pH of all
these solutions was also talnsn to determine the changes. if any.
in fl upon the addition of sodium chloride and sugars.

Ior sad: acid a series of seven solutions was made. the first
containing only the acid and the remaining six the sense concentration
of acid plus the concentration of other substances (M and sugars).

the results of this set of determinations are recorded in Table 35.

Results
hiresholds of Sensation
fhetequency distribution of sensitivity and taste threshold
values of the substances listed in fable 11 are given in Tables
12, 13. and lh.
be second set. Tables 15, 16. and 17. is given as the geo-
metric means of the frequency distributions. It was found that

in this way the results could be most accwately expressed. The

molar concentrations are the geometric means of the frequency
distribution of the respective substances. 'i'he per cent con-
centration was determined from the molar concentration. l'or
the determination of the relative weight. the first substance
listed was nbitrarily taken as the unit and the remaining
substances determined by simple preportions. 'Percentage'
gives the relative effectiveness in terms of the first sub-

stance listed.

47..

 

 

 

 

lfable 12. frequency distribution of sensitivity and taste thres-
hold values for salt solutions.
P Salts
Iolar
cone. lacl . Cadiz 11013 $01“
0.000075 ill-1
0-0001 10.7
0.00025 u-o 8-11;
0.00050 16-3 0-8
O. 0007 5 11-17 M ‘
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~55-

Discussion
‘l‘here is little that need be written regarding the frequency
distribution of the substances. In met cases, they follow a
normal distribution curve. It was intended that few or none of the
Judges should note aw difference between the first solution and
distilled water and usually this was the case. However, little
weignt was given to the exceptions since doubtless imagination and

other pqchological factors were of considerable importance.

sum taste:

It is evident from table 15 that intensity of taste of salts

 

is dependant upon both, the anion and the cation. It would be """""‘
expected that stannic chloride would be stronger in tastethan sodiun
chloride by virtue of having four chlorine ions per molecule as com-
pared to one for sodium chloride but this seems insufficient reason
to account for stannic chloride being 32 times as strong as sodium
chloride. mould we aeeune that the anion is responsible for the
intensity of taste of salts. then how is it possible to account for
the relative intensity of calcium daloride and stannic chloride?

It seems only reasonable to conclude that intensity of taste
of salts rests with the particular combination of anion and cation.
However, it mould be noted that the chlorides did not all possess
the sale taste. Sodium chloride was alqu described as salty. Cal-
ciun chloride use most frequently described as salty but in some
cases it was described as a bitter salt. and unknown taste. Aluminum

chloride received the following descriptions, in order of frequency:

-56..

sour taste. slum taste and bitter taste. lhe order of frequency for
description of stannic chloride is sour taste, bitter taste. and

salty taste.

Sour taste:

According to the results (Table 16). Crosier's (1916 d1918a 5 b)
explanation of sour taste seems to be somewhat inadequate. Taylor
(1927) found the order of penetration of acids into the tissue to
be Hal lactic tartaric malic citric acetic. from this work,
the order of intensity of taste was 361 lactic malic tartaric
acetic citric. However. where there are differences in the order,
upon doser examination of Table 16 and figure 5. the difference is
small and possibly new be attributed to experimental error. Gon-
sequently. Orozier's explanation may be of some value.

fable 16 otherwise is self explanatory. There is a relation-
diip between the intensity of the taste of the acids and the amount
of acid necessary to bring 10 ml. of phosphate buffer solution to

pl th5 but this is referred to later in this paper.

lagers:
here is little that need be written about the relative taste

potency of sugars: fable 17 is self explanatory. The value for
dextrose is somewhat higier than other workers have found (Table 9)
while the fructose value is lower. Lactose is about at the average
figure while maltose tends to be sonevdiat lower. Generally, the

results on the sugars correspond with the range of values found in

 

-57..

the literature.

his work on salt and sugars is not new, the field having been
well covered by other workers but each was taken individually, that
is. one worker studied sugars, or acids alone. In this work all
three substances were studied individually and then in combination

with each other using the same methods and the same Judges.

Buffer titrations:

figures 10 and 11 show the curves of the various acids titrated
Against the phosphate buffer. The sourness of each acid can be com-
pared by following amr line on the vertical axis. Referring back
to table 16 and using hydrochloric acid as the reference acid the
accuracy of these titrations can be checked.

he results of the titrations check fairly well with tests
except in the case of tartaric acid. ihe differences, with the
exception of tartaric acid. are sufficiently small so as to be
attributed to experimental error since these differences could not
be readily detected by Judges. However, tartaric acid shows sud: a
great difference that it makes the entire method somewhat questionable.

Table 18. Accuracy of titration against a phosphate buffer.

Acid lqui sour by taste uni sour by titration
H01 .0078 .0078
Lactic .00085 .0007!
Ialic .00075 .00065
Tartaric .00070 .0065
Acetic .00210 .00230

citric . 00070 . 00062

 

 

“of

-53..

Competition or Compensation

more are 16 tables giving the results of the experiments to
determine the effect upon taste of one substance upon another. The
first series of four tables (fables 19-22) comprises the results of
the first method as previously described and Tables 23-31; give the
results of the second method for these determinations.

l'cr aid in interpreting fables 19-22. the reader is referred ! '
to direction data sheet lo 2 (p. in). These figures represent the 2
results of the taste of the combined solutions given in the tables

cogered to the taste of the control (solution one).

 

Yin-H.411 -W Ir."
!

In the second set of tables (Tables 23-310. the first column
in each table indicates the substance that was tasted and the in-
fluence upon that sub stance of sub-taste threshold concentrations of
sodium chloride. the various acids and sugars. This was done by
Intching experiments as previously described. be second and third
colunns describe the composition of the solution referred to as the
unknown. Columns four and five indicate the molar concentrations of
the solutions to which this unknown was matched. n1. last two colmms.
six and seven. give the results of these matchings. l‘or example.
table 23 shows the influence of sodium chloride upon the various acids
and sugars. In this table. column one shows acetic acid as the sub-
stance being tasted. Columns two and three show that 0.01 M laCl was
added to 0.005 I acetic acid. ibis solution was called the unknown
since the Judges had no howledge of its composition. Columns four
and five indicate the molar concentration and the interval of range of

the acetic acid. e.g.. 0.0045. 0.0050. 0.0055 and 0.0060 respectively.

to which the mknown solution (columns two and three) were matched.
The results as given in the last two columns show that of ten Judges.
eight matched.the unknown solution to 0.0005n acetic acid. one
matdied it to 0.00M]! acetic acid. and one matched it to 0.0050
acetic acid. Consequently. at these concentrations. sodium chloride
reduced the sourness of acetic acid.

fable 19. Iffect of molar sub-taste threshold concentrations of

acetic acid upon the taste of molar concentrations of
sodium chloride.

Solution lost frequent
number bdium chloride conc. Acetic acid conc. effect

1 0.050 0 control

2 0.050 0.0001 -1

3 0.050 0.00025 -1

h 0.050 0.0005 0

5 0.050 0.00075 e l

6 0.050 0.0010 e 2

fable 20. Effect of molar sub-taste concentrations of sodium chloride
upon the taste of molar concentrations of acetic acid.

blut ion In st frequent
number Acct ic acid conc. Sodium chlor ide conc . effect

1 0. 0050 0 control

2 0.0050 0.0025 0

3 0.0050 0.0050 o

h 0. 0050 0.0075 --1

5 0. 0050 0. 0100 -2

6 0.0050 0.0250 .3

fable 21.

lilut ion
umber

O‘W-E'WNH

Sable 22.

blut ion
number

mmrumfl

-60-

Effect of molar sub-taste threshold concentrations of
dextrose upon the taste of molar concentrations of

soditn chloride.

flodiun chloride conc .
0.050
0. 050
0. 050
0. 050
0. 050
0. 050

Dextro ee cone.

0
0.010
0.025
0.050
0. 075
0.100

lost frequent
effect

0
O

lffect of molar sub-taste threshold concentrations of
dextrose upon the taste of molar concentrations of

acct ic acid.

Acetic acid conc

0.0050
0.0050
0.0050
0.0050
0.0050
0.0050

Dextrose conc.

0
O. 010
0.025
0. 050
0. 075
0.100

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-73-

hble 35. Ithe effect of the addition of sodium chloride and
sugars upon buffer titration and pH of acids.

lolar conc. lolar cone. of I1. acid pH before
of acid substance added necessary buffer
buffer pH 14.115 added
0.0010 301 21.0 3.00
0.025 31101 20.5 3.03
0.075 Dextrose 20.7 3.03
0.015 Sucrose 20.6 3.05
0.100 Lactose 21.3 3.02
0.0110 Fructose 21.0 3.06
0.060 laltoee 21.0 3.01
0.005 Acetic acid 30.8 3.56
0.025 3.101 31.2 3.57
0.075 Dextrose 303* 3.59
0.015 Sucrose 31.1 3.55
0.100 Lactose 30.3 3.60
0.0160 huctose 30.5 3.59
0.060 Maltese 30.7 3.55
0.001 Citric acid. 25.2 3.27
0.025 Heel 25.5 3.30
0.075 Dextrose 25.0 3.25
0.015 Sucrose 214.8 3.28
0.100 Lactose 25.0 3.26
0.0140 Fructose 25.1 3.28
0.060 Maltese 25.3 3.30
0.003 M10 801d 7305 3010
0.025 lacl 72.0 3.05
0.075 Dextrose 73.0 3.09
0.015 Sucrose 71+.0 3.10
0.100 Lactose 714.2 3.07
0.0110 metosa 73e9 3e08
0.060 Haltose 72.5 3.12
0.03 Tartaric acid 92.0 2.93
0.025 I501 93.2 2e97
0.075 Dextrose 92.8 2.95
0.015 Sucrose 91.5 2.91
0.100 Lactose 92.7 2.91}
0.0140 Fructose 93.1 2.95
0.060 maltose 92.2 2.96
0.003 Lactic acid 60.3 3.22
0.025 159.01 59.5 3.20
0.075 Dextrose 61.0 3.18
0.015 sucrose 61.2 3.26
0.100 LaCtO'. 60.8 3e22
0.01m fructose 59.7 3.21
0.060 [altose 60.9 3.211

 

-71...

Discussion

fable 19 shows that when the concentration of acetic acid
approaches the sensitivity threshold its effect in increasing the
saltiness- of sodim chloride was discernible to the Judges.
Above the threshold the increase in taste became greater.

table 20 shows that in the range where the Judges were sensitive
to sodiun chloride. it acted to reduce the course» of acetic acid
and this action was increased with increasing concentrations of

sodium chloride.
In tables 21 and 22 the taste of both sodium chloride and

 

acetic acid was reduced by the action of sub-taste threshold con- .__________

centrations of dextrose. It would seem the effect of dextrose was

greatest on sodium chloride. the effect was likewise noticeable

only when the concentration was beyond the sensitivity threshold.
Sodiun chloride in sub-taste threshold concentrations con-

sistently reduced the sourness of all the acids tested but to

"trying degees. (Table 23) It reduced the sourness of acetic.

hydrochloric and citric acids only moderately but sufficiently

for a noticeable taste difference. Ihile with malic. lactic and

tartaric acids, sodium chloride exhibited a marked effect in reducing

sourness, very much geater than with the other acids. .
he effect of sodium chloride upon the taste of sugars (Table 23)

was Just the opposite since an increase in sweetness was noted by

the Judges for all the sugars. 0n the basis of molarity. the

relative increase in sweetness of the sung was fructose lactose

-75..

and mltose dextrose sucrose. 0n the basis of concentration
by weight. the relative effect of sodium chloride is maltose
and lactose fructose dextrose sucrose.

i'able 2h shows the effect of hydrochloric acid upon the
taste of sodium chloride mid sugars. Hydrochloric acid showed no
effect on the taste of sodium chloride. reduced the sweetness of
dextrose and left sucrose and fructose unchanged but with a
tendency toward a decrease in sweetness.

It is interesting to note that hydrochloric acid has no effect
upon the taste of sodium chloride. If the intensity of taste of
eodius chloride was a result of the chlorine ions, then hydro-
chloric acid should. if anything, increase the taste of salt by
the addition of chlorine ions. Seven of ten Judges could notice
no change in taste and three Judges noted a reduction in taste.

If the tendency is for a reduction in taste. it would seem that
the sodium ion has considerable to do with the intensity of taste
of salt since the sodium ions are reduced by the action of a
semen ion. this is also indicated in the subsequent tables where
the effect of other acids upon the taste of sodium chloride is an
increase in saltiness.

table 25 flows that lactic acid in sub-taste threshold con-
centrations increased the saltiness of sodium chloride and reduces
the sweetness of fructose. Dextrose remained unaffected while the
sweetness of sucrose was increased.

Tartaric and malic acids in sub-taste threshold concentrations

 

Innis f... 3.3'
It

-75-

have the same effect as lactic acid on the taste of sodium
chloride. fructose, dextrose and sucrose as shown in Tables 26
and 28. fhese three acids acted very much alike throughout
the entire experiments.

.‘l'able 29 shows the action of sub-taste threshold concen-
trations of citric acid on sodium chloride. dextrose, sucrose
and fructose. The saltiness of sodium chloride was increased, T
the sweetness of dextrose and fructose unchanged and sucrose in-
creased.

Certain generalities can be drawn from the results of the

 

effect of sub-taste threshold concentrations of acids. he a...”
organic acids increase the saltiness of sodium chloride. 'ith
the exception of acetic and hydrochloric acids. the sweetness of
dextrose remained unchanged. while the sweetness of sucrose was
increased. All the acids but hydrochloric acid reduced the sweet-
ness of fructose.

i‘ables 30 through 3h show the effect of sugars in sub-taste
threshold concentrations upon sodiun chloride and the different
acids. All the sugars reduced the saltiness of sodium chloride
about equally well. use sourness of acetic acid was reduced by all
the sugars with fructose showing the geatest effectiveness. he
action of the sugars upon the sourness of hydrochloric acid and
citric acid was an approximately equal reduction in sourness.
Lactic acid. malic acid and tartaric acids showed the greatest

reductions in sourness upon the addition of sugars. Sucrose was

-77..

the most effective of the sugars in reducing sourness of malic
and tartaric acids in the concentrations used. However. the
same concentration of all sugars did not have the same effect.
Both acetic and hydrochloric acids have little if any effect
upon the sweetness of sucrose as shown in tables 21% and 28.
Lactic. malic. tartaric and citric acids affect the taste of
sucrose by increasing the sweetntee (fables 21$. 25. 26, and 28).
his was checked by use of a polariscope to determine if inversion
of the sucrose took place at their respective concentrations and
no inversion of sucrose could be noted.
Table 35 shows that the decrease in sourness upon the addition
of sodium chloride and sugars to acids can not be measured by

changes in buffer titrations of pH.

memory

l. his order of effectiveness of taste for salts was stannic
chloride) aluminms chloride) calcium chloride) sodium chloride.
however, the differences were such that it is likely that intensity
of taste rests with both the cation and anion.

2. he results indicate that ability to penetrate tissues. pH.
and effectiveness against phosphate buffers were all factors in-
volved in the sourness of acids and that no single factor can be
used to measure sourne'ss.

3. he order of effectiveness of taste for acids was hydro-
chloric acid>lactic acid) malic acid) tartaric acid> acetic acid)

citric acid. Specific values for each are given.

 

-72..

14. he order of effectiveness of taste for sugars was fructose)
sucrose) dextrose)malt0se )lactose. Here also specific values

for each are given.

5. The effect of sodium chloride. as indicated in the results.

was to reduce the sourness of acids and to increase the sweetness

of sugars. 'Ihe reduction of sournees of acids was particularily
noticeable for lactic, malic and tartaric acids.

6. 'ith the exceptions of hydrochloric and acetic acids. where a
reduction in sweetness was noted. acids showed no effect upon dextrose.

7. Generally, acids tend to increase the saltiness of sodium

 

chloride. However, Ivdrochloric acid was the exception and showed L”
no effect upon salt.

8. Hydrochloric and acetic acids had no effect upon the taste of
sucrose while the remaining acids increased its sweetness. It was
found that at the concentrations used, the acids caused no inversion
of the sucrose as measured by the polariscope.

9. The sweetness of fructose was reduced by all the acids except
hydrochloric and citric acids where no change in sweetness could

be noted.

10. All the sugars acted to reduce the saltiness of sodium chloride.
11. All the sugars reduced the sournees of the acids but to varying
degrees. Lactic, malic and tartaric acids were outstanding in this
respect.

12. no effect of sodius chloride and sugars upon the sourness of
acids could not be correlated with changes in phosphate buffer

titrat ions nor with changes in hydrogen ion concentration.

-79-

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