Group 3 Monday Morning Biological Laboratory

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Group 3 Monday Morning Biological Laboratory

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Group 3 Monday Morning Biological Laboratory

ACKNOWLEDGE



We would like to express my deepest appreciation to all those who provided me

the possibility to complete this report. A special gratitude we give to our
teaching assistants, Mr. Trung and Miss Duyen, whose contribution in
stimulating suggestions and encouragement, helped us to coordinate our project
especially in advising our experimental methods.

Furthermore, we would also like to acknowledge with much appreciation the

crucial role of all classmates, who share with us the experimental data to
complete the report. Last but not least, many thanks go to the head of the
project, our instructor, Mrs. Ha Thi Thanh Huong, whose have invested her full
effort in guiding the team in achieving the goal especially in our project that has
improved ourselves thanks to her comment and advices

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SUMMARY OF THE REPORT

“TASTE RECEPTOR AND TASTE MODIFIER”

Introduction:
• Sense of taste is formed thanks to taste receptors organized into taste buds in mouth
especially on surfaces of the tongue and palate while the taste buds, composed of taste
cells (gustatory cells), play a role in detecting the different tastes (Sour, Salty, Bitter,
Umami, Sweet)
• Miracle Fruit is a taste modifier which has the ability to make sour foods taste sweet,
which is explained that its miraculin protein changes shape when exposed to acids by a
group of Japanese and French researchers
• By three basic principles: randomization, replication and local control, we designed our
experiment in order to verify the effects of miracle fruit to different types of tastes and in
different conditions (temperature, concentration, pH) and how long the effect lasts.
Material and method:
With 10 miracle fruits and 8 different-type-of-taste samples for the whole class, four groups
share the work and result together following this procedure:
• Step 1: Eat the samples without miracle fruit for local control.
• Step 2: One team, using 4 miracle fruits, eats 8 different-type-of-taste samples in four
random chains and the other team using 6 miracle fruits eats sour samples in 6 different
conditions (high/low temperature, high/low concentration, high/low pH). Each test is
carried out three times, the next time is 45 seconds later compared to the previous one.
Result and discussion:
In the experiment 1 to test the effect of miracle fruit to different types of taste: It is same as the
theory that miracle fruit has the ability to make sour foods taste sweet and can not change other
types of taste and we cannot test the washability in this experiment due to short-term tests.
In the experiment 2 to test the effect of miracle fruit on different conditions: The efficiency of the
effect is changed when its environmental factors change because the miraculin inside (most cruel
factor to form this effect) change its structure.
Conclusion:
By practical test, we can conclude that Miracle Fruit has the ability to make sour foods taste
sweet and this effect’s efficiency can be changed based on the environmental factors
(temperature, concentration and pH).

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Contents
ACKNOWLEDGE .............................................................................................. 3
SUMMARY OF THE REPORT........................................................................ 4
I. Introduction ............................................................................................... 6
1. Sense of taste ............................................................................................................................... 6
2. Miracle fruit, ............................................................................................................................... 9
3. Basic principles of experimental designs .................................................................................. 10
4. Objective ................................................................................................................................... 11
II. MATERIAL AND EXPERIMENTAL DESIGN ................................. 12
1. Material ..................................................................................................................................... 12
2. Experimental design – Protocol: ............................................................................................... 12
III. RESULT AND DISCUSSION ................................................................ 13
1. Experiment 1: Verify some traits of the effect of miracle fruit on different types of taste ....... 13
2. Experiment 2: Verify some traits of the effect of miracle fruit on different conditions ........... 14
IV. CONCLUSION: ....................................................................................... 19
REFERENCES .................................................................................................. 20

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I. INTRODUCTION

1. Sense of taste
Unlike touch, vision, audition, or olfaction, which function in diverse behavioral contexts,
the sense of taste has evolved to serve as a dominant regulator and driver of feeding
behavior. Gustatory systems detect nutritionally relevant and harmful compounds in food
and trigger innate behaviors leading to acceptance or rejection of potential food sources.
Taste is therefore a powerful system in which to ask the question, how is sensory
input transformed and distributed to evoke a specific behavioral output?
a) The mammalian taste systemi
Humans, and probably most mammals, categorize taste stimuli into a small palette of
qualitiesii. The tastes of sweet, bitter, sour, and salty are familiar to all, while umami,
a savory taste elicited by certain L-amino acidsiii, constitutes a fifth “primary” taste
modality. Umami and sweet are “good” tastes that promote consumption of nutritive food
(such as the building blocks for protein synthesis and energy), whereas bitter and sour are
“bad” tastes that alert the organism to toxins and low pH, promoting rejection of foods
containing harmful substances (for instance, noxious plants or spoiled or unripe fruits). Salt
can taste either “good” or “bad” to us and be attractive or repulsive to mice, depending both
on the concentration of sodium and on the physiological needs of the tasteriv. The function of
the taste system is greatly impacted by olfaction, texture, and the internal state of the
organism. Indeed, our own taste perceptions are richly modulated by hunger, satiety,
emotion, and expectation.
b) Taste receptorv
Taste receptor cells (TRCs) are found in the mouth and are concentrated on surfaces of the
tongue and palate. TRCs are organized into taste buds, ovoid structures typically composed
of 50–100 cellsvi. On the tongue, taste buds are housed within epithelial structures termed
papillae, of which there are three types: (1) dozens of taste buds are distributed across the
anterior surface of the tongue in fungiform papillae, (2) hundreds are located in the trenches
of circumvallate papillae at the back, and (3) dozens to hundreds more localize to the sides of
the tongue in foliate papillae. Many isolated taste buds are also distributed on the soft palate.
The taste buds are housed on the papillae of the tongue where taste receptors are able to
detect different chemicals. There are other taste receptors on the palate, epiglottis and upper
esophagus but it is the receptors on the tongue that are the primary organ of taste. The taste
buds are found on three types of tongue papillae:
- Vallate at the back of the tongue (posterior)
- Fungiform on the apex and body of the tongue (anterior)
- Foliate on the sides of the tongue (lateral)
The most numerous papillae on the tongue, filiform, do not contain any taste buds.
The taste buds distributed throughout the tongue play a role in detecting the different tastes
although there are certain areas that are more sensitive for specific tastes. The posterior part of

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the tongue, which contains the largest number of taste buds, is sensitive to sour and bitter
tastes. The apex of the tongue to sweet tastes while the sides (lateral) are sensitive to saltiness.
A taste bud is composed of specially modified epithelial cells known as taste
cells (gustatory cells) which are surrounded by supporting sustentacular cells. The taste
cells extend a number of small hair-like structures known as microvilli into a minute taste
pore. These pores are the openings in the tongue that allow substances dissolve in the saliva
to make contact with the microvilli.

Picture 1: Structure of the Taste Bud - Health Hype.

The human tongue has between 3,000 to 10,000 taste buds. Each taste bud is about 0.03
millimeter in diameter and about 0.06 millimeter in length. Children have the most amount
of taste buds and after the age of approximately 45 years, many taste buds begin to
degenerate.
The microvilli are the receptor surface of the taste cells and responsible for detecting
tastes. Food is dissolved in the saliva in the mouth and this solution is then able to slip into
the pores where it stimulates the receptors of the taste cell microvilli. When stimulated, ion
channels on the taste cell open thereby allowing positively charge sodium or hydrogen ions to
enter. The inner surface of the taste cell membrane, which is negatively charged, is
depolarized by the influx of positive ions. The extent of the depolarization corresponds to the
concentration of the substance that stimulates the specific receptor. Vesicles within the taste
cells release neurotransmitters from its inner surface which stimulate the surrounding
network of nerve fibers. This discharges impulses which travel to and stimulate certain areas
of the brain. This allows for the perception of taste. Initially the rate of discharge increases till
it peaks within a fraction of a second. It then adapts and the discharge rate decreases but

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continues thereby passing a weaker continuous signal until the substance is removed or the
receptor accommodates. This is the reason why initially tasting a substance elicits the most
prominent taste which subsequently decreases in intensity.
c) Types of tastevii

The taste cells have varying number of receptors that are stimulated by several different
elements and compounds, namely adenosine, chloride, hydrogen, inosine, potassium, sodium
and glutamate. These chemicals will trigger the depolarization of the taste cell membrane. In
addition, there are specific receptors that detect bitter and sweet which indirectly trigger the
depolarization by the action of secondary messengers. This accounts for five primary tastes of
human - sweet, salty, sour, bitter and umami (also known as savory).
• Sour taste – hydrogen ions
• Salty taste – ionized salts (anions and cations), especially sodium ions.
• Sweet taste – sugars, glycols, alcohols, aldehydes, ketones, amides, esters, some amino
acids, some small proteins, sulfonic acids, halogenated acids, and inorganic salts of lead
and beryllium.
• Bitter taste – organic substances, especially long-chain organic substances that contain
nitrogen and alkaloids.
• Umami taste – foods containing l-glutamate.

Picture 2: Taste receptor diagram - Box writing diagram

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Picture 3: Modulation of sweet taste sensitivity by orexigenic and anorexigenic factors -

Masafumi Jyotaki, Noriatsu Shigemura, Yuzo Ninomiya.

2. Miracle fruitviii,ix
Miracle fruit, (Synsepalum dulcificum), also called miracle berry, evergreen shrub of the
family Sapotaceae, grown for its mild fruits that make subsequently eaten sour foods taste
sweet. The miracle fruit plant is native to tropical West Africa, where it is used locally to
sweeten palm wine and other beverages. The unrelated sweet prayer plant (Thaumatococcus
daniellii) is also known as miracle fruit for its similar ability to make sour foods taste sweet.
The miracle fruit plant grows as a dense shrub or small tree, usually not more than 5.5
meters (18 feet) in height in the wild and generally smaller when cultivated. The
simple leaves are oval and tapering at the base with smooth margins and feature a waxy
underside; they grow in spirelike clusters at the ends of small branches. The small
white flowers give rise to red drupe fruits that are about 2–3 cm (0.8–1.2 inches) in length.
Plants typically begin producing fruit after three or four years and require acidic soil.
The flavor-altering mechanism of miracle fruit is due to a glycoprotein named miraculin,
which was first isolated by Japanese researcher Kenzo Kurihara in 1968. Miraculin is a
glycoprotein (a protein that has a carbohydrate group attached to the polypeptide chain) that
has been isolated as the potent component of the Miracle Fruit that alters taste perception by
binding to sweet receptors on the tongue. Miraculin is the largest known macromoleculex that
can influence taste perception. The molecular weight of miraculin is 24,600 Da, which
includes 86.1% polypeptide and 13.9% carbohydrate. The complete sequence of the 191
amino acid single polypeptide portion of the molecule has been identifiedxi. Although
miraculin itself is not sweet, it binds to receptors on the taste buds and causes acidic foods to
be perceived as sweet. The effect typically lasts from a half hour to two hours, with the
intensity declining over time.

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Picture 4: Miraculin chemical structure. Molecular Formula: C88H146N26O34 - Ensign

chemical.
A team of Japanese and French researchers working together have solved the puzzle and
have published the results of their efforts in the Proceedings of the National Academy of
Sciences. The team grew human kidney cells in a dish that were engineered to produce
sweet receptor proteins. They then applied a chemical that caused the receptor cells to light
up when activated. Next, they applied miraculin, the protein in miracle fruit that is
responsible for the sweetening effects. After that they added different substances with
different pH levels and found that the miraculin had three distinct impacts on the receptors.
At low levels there is little effect, at medium levels the miraculin boosted response and at
high levels the receptors were activated on their own.
This all happens, the researchers say, because the miraculin protein changes shape when
exposed to acids. The higher the level, the more it changes shape. And because the protein
binds very strongly to the receptors in the human tongue, those changes in shape change the
way the receptors react when acids are introduced into the mouth. The bottom line is, the
higher the pH level in a substance, the sweeter it tastes to the person doing the tasting.

3. Basic principles of experimental designs

The basic principles of experimental designs are randomization, replication and local
control. These principles make a valid test of significance possible.
• The first principle of an experimental design is randomization, which is a random process
of assigning treatments to the experimental units. The purpose of randomization is to
remove bias and other sources of extraneous variation which are not controllable. Another
advantage of randomization (accompanied by replication) is that it forms the basis of any
valid statistical test.

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• The second principle of an experimental design is replication, which is a repetition of the

basic experiment. This type of variation can be removed by using a number of
experimental units. We therefore perform the experiment more than once, i.e., we repeat
the basic experiment. An individual repetition is called a replicate. The number, the shape
and the size of replicates depend upon the nature of the experimental material. A
replication is used to:
o Secure a more accurate estimate of the experimental error, a term which represents
the differences that would be observed if the same treatments were applied several
times to the same experimental units;
o Decrease the experimental error and thereby increase precision, which is a measure
of the variability of the experimental error; and

o Obtain a more precise estimate of the mean effect of a treatment, since  2 y = ,
2n
where n denotes the number of replications.
• The main purpose of the principle of local control is to increase the efficiency of an
experimental design by decreasing the experimental error.
In the taste testing experiment, we applied these principles during the experiment as:
• Randomization and replication: As there were 8 different food and 8 people involved in
the experiment, each person tasted the food without eating miracle fruit. After that, they
ate miracle fruit and tasted. Each of them would try 2-3 kinds of food and then rated the
tastes, repeated until all tastes had enough rates from 4 people.
• Local control: Tasted each kind of food in 15 seconds, rated the taste, drank some water,
and waited for 10 minutes then tried others one.

In the effect dependence experiment, we also applied these principles:

• Randomization and replication: 2 people would test 1 effect, which divided into 2 sub-
effects. Each person tried passion fruit and rated for the base line. Then ate miracle fruit
which had been made to fit the requirement in the test, tried again the passion fruit, rated
the taste. Repeated 3 times.
• Local control: Tasted in 15 seconds, rated the taste, drank some water, and waited for 45s
and tried again.

4. Objective
• Acknowledge about types of taste, identify these types between different food samples.
• Learn about mechanism of taste (receptors in human’s tongue) by rating and comparing
with others.
• Understand properties of miracle fruit. Explain the mechanism of miracle fruit. Test and
compare with the theories. - Apply principles in designing and carrying out the
experiment.

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II. MATERIAL AND EXPERIMENTAL DESIGN

1. Material
• Miracle fruits: 10 objects (for the whole class)
• Salt (1) • Passion fruit juice (5)
• Sugar (2) • Candy (6)
• Mono sodium glutamate (MSG) (3) • Chilly pepper (7)
• Passion fruit (4) • Concentrated tea (8)

2. Experimental design – Protocol:

Due to the fact that the number of miracle fruit provided is limited at only 10 left, our group
needs to cooperate with other groups to collect enough significant data for this experiment.
As a result, the experimental design is approved by all members in class as follows:
Team 1 (Group 1 & 2) – Using 4 Team 2 (Group 3 & 4) – Using 6 miracle
miracle fruits fruits
Objectives Verify what types of tastes are Verify the effect of miracle fruit in different
modified by the miracle fruit, whether conditions (temperature, pH and
the effect is washable and how long concentration)
the effect lasts.

Procedure Step 1: 4 people joining in the Step 1: 6 people taste passion fruit juice and
experiment taste all 8 samples randomly rate its sour intensity as the baseline for local
to find out the main type of tastes of the control.
following sample then rate the taste Step 2: They eats 6 miracle fruits in 6
intensity as the baseline. (Local control) different conditions:
Step 2: They eat 1 miracle fruit for each • In high/low temperature (100oC - heat
person then they test the taste of 8 in microwave for 1 minutes and 0oC
samples in different, random chains freezing in fridge for 30 minutes);
three times (the next time is 45 seconds • In acidic/basic environment (massed
later than the previous one), give the in lime juice – pH<7 and isotonic
comments and rate the taste intensity in drink – pH>7)
points after each test. • With large/small concentration of
The chains are random and described fruit (1.75 fruits and 0.25 fruits for
below: each test)
1st: - One condition for each test.
(1)→(2)→(3)→(4)→(5)→(6)→(7)→(8) Step 3: They test the taste of passion fruit
2nd: juice three times (the next time is 45 seconds
(2)→(3)→(4)→(5)→(6)→(7)→(8)→(1) later than the previous one), give the
3rd: comments and rate its sour intensity in points
(3)→(4)→(5)→(6)→(7)→(8)→(1)→(2) after each test (compared to the baseline).
4th:
(4)→(5)→(6)→(7)→(8)→(1)→(2)→(3)
Demands After eating a miracle fruit, the sample is chewed and suck in mouth for 15 seconds to
for each test feel the taste, give the comment, rate the taste intensity. Then they (who joining tasting
the samples) wait for 45 seconds in rest and drink pure water for the next test to test the
washability of the effect.
Table 1: Description of Experimental design.

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III. RESULT AND DISCUSSION

1. Experiment 1: Verify some traits of the effect of miracle fruit on
different types of taste

After doing experiment, team 1 shares with us their data on the table 1.
Rating of the taste intensity after
Rating of taste intensity
Sample Type of eating miracle fruit
without eating miracle
taste Test Test Test
fruit (Baseline) Average
#1 #2 #3
Passion fruit
Sour 8/10 6 6 8 6.67
juice
Lime Sour 9/10 7 8 8 7.67
Sugar Sweet 8/10 5 6 6 5.67
Candy Sweet 9/10 4 4 5 4.33
Monosodium
glutamate Unami 5/10 8 8 8 8
(MSG)
Salt Salty 9/10 10 10 10 10
Chilly pepper Salty 10/10 10 10 10 10
Concentrated
Bitter 10/10 9 10 10 9.67
tea

Table 2: Result from Team 1’s experiment

12
RATING OF TASTE INTENSITY

Baseline Avatage Rate after eating

10
10 10 10 10 9.67
8 9 9 9
8 7.67 8 8
6 6.67
5.67
4 5
4.33

0
Passion Fruit Lime Sugar Candy MSG Salt Chilly Pepper Concentrated
tea
SAMPLE TEST

Result from team 1's experim ent

Comparing the baseline in the result, there is the information of those sample tastes and our
intensity rating as basic and primary data for applying more advanced experiments. The result
in the third column, which is average value by testing significant times, was rated depend on
the sensitive feeling of testers. All the tests must be highly rated as original and direct tasting
test. Nonetheless, MSG test have a smaller result. In this case, it can be explained that the
testers have low sensitivity with umami taste or amount of MSG is not enough to create taste
identification.

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Analyzing the difference between before and after eating the miracle fruit, the sour
intensity is highly changed, decrease in Passion fruit juice sample and in Lime sample.
There are not any significant differences in MSG, Salt, Chilly Pepper and concentrated tea
samples, which means that the effect of the miracle fruit is highly performed when it reacts
with acid and change the structures of acids, which forms the sour taste. In case of sweet
sample (Sugar and Candy), the miracle fruit makes food sweeter, which can be explained by
that miracle fruit is also sweet and it is washable for a long term (15 minutes to 2 hours).
The main purpose of this experiment is determining which taste can be affected by miracle.
The principle is that "More rating, more taste intensity", which means if the rating is high, the
testers can easily to recognize the original taste of the samples (data in Table 1) after using
Miracle fruit and we could see that miracle cannot change food’s types if taste instead of sour
food become sweet.. We do this experiment to check the accuracy of the previous studies.
In theory, Miracle only has impact to sour taste, so the low rating of sour samples, i.e passion
juice (avg: 6.67) and lime (avg: 7.67) sample, is actually evident and can be understand easily.
Similar to MSG, salt, chilly pepper and concentrated tea sample, their rating is also high (avg
respectively: 8, 10, 10 and 9.67), which means tester can identify the taste of those samples
without difficulty.
There are many special situations that is far away from what we expect to see, the rating for
sugar and candy sample, which both is sweetness sample, is significantly low (lower than
passion juice and lime results). There are many issues to explain these situations. Firstly, this
test rating depends on the sensibility of testers, or we can call this is a subjective experiment.
Second reason can be the quantity of each sample is not enough to create the taste indication.
Besides, there can be some mistakes in recording the results, or in performing test procedure.
Otherwise, the sweetness sample can also be affected by Miracle fruit. However, this argument
seems to be opposite to the previous opinions.
Finally, we can make sure to conclude that sour taste is strongly affected by the glycoprotein
in Miracle fruit. Basing on our above experimental results, so is sweet taste (but it is still an
uncertain conclusion).

2. Experiment 2: Verify some traits of the effect of miracle fruit on

different conditions

The order Ranking sour

Condition
of test intensity Phenomenon Explanation
Baseline 7/10
pH ~ 2 (lime
pH 1st time 7/10 The result seem a Both result run around the
juice)
little higher than the baseline value, which
2nd time 8.5/10
baseline, and means low value of pH

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decrease after many and larger value of pH

3rd time 9/10 testing time. can affect to the activity
of Miraculin. Miraculin
can be considered as an
Baseline 7/10 Phenomenon enzyme, so that it have an
optimal range of
1st time 7/10 activation condition.
2nd time 8/10 The average of these Therefore, when we
rating is almost equal decrease pH value or
to the baseline value increase pH value,
and seem to be the specially into very acidic
same to all three pH, it can be over the
pH ~ 7.5 times testing. optimal range, so that it
(Enviroment will be inactivated.
: Revise of Furthermore, the acid in
Pepsico.) At first, we expect the treatment (from lime
3rd time 7/10 that Revive 7 up will juice and revive) can be
have a basic pH, affect to results.
however, it is acidic
pH, so we have to → Larger pH, less
move on and activation.
continuous the And the optimum pH for
experiment. this effect is between 2
and 8

Baseline 7/10 Phenomenon Explanation

1st time 2/10 We can recognize

that at a high
2nd time 1/10 concentration of More amount of miracle
miracle fruit can lead fruit, more amount of
to a high effect in miraculin binding to taste
1.75 of fruit
inducing sweet taste, bubs, and more sweet
which lead to low feeling to the tester. It is
3rd time 2.5/10 rating for this sample opposite to low amount of
Concent miracle fruit. Small
(hard to identify the
-ration concentration cause many
sourness from passion
juice). difficulties for Miraculin
to approach taste
Baseline 7/10 Phenomenon receptors and have small
effect in inducing sweet
1st time 7.5/10 Low concentration of taste.
0.25 of fruit miracle fruit can
2nd time 8/10 reduce the ability to → Higher concentration,
induce sweet taste and higher activation.
3rd time 9/10 shield sour taste,
which lead tester still

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be sensitive with the

sourness from passion
juice, (the rating is
actually high).

Baseline 7/10 Phenomenon Explanation

1st time 9/10 In case we reduce the

temperature (to -10oC), at
2nd time 6/10 the begin Miraculin
molecules move slowly,
Low temperature test so their effect decrease,
Low (-10oC) have the decrease and the rating is high and
rating over tasting tester can easy to detect
3rd time 5/10 time. the sour taste. Then after
many tasting time,
temperature can increase
so that Miraculin can
come back to activation
Baseline 7/10 Phenomenon condition, so the rating is
lower in last tasting tests,
1st time 8.5/10 which means Miracle
fruit has shield the
Tempera 2nd time 9/10 sourness.
ture However, in case we put
miracle fruit into boiling
water, the protein will be
destroyed instead of
increase activation. High
In high temperature, temperature can denature
High the rating is always protein, and change its
(100oC) high, which means conformation, so that it
the effect of miracle loses it function.
3rd time 9.5/10 fruit was destroyed. Therefore, the rating is
always high during the
high temperature test.
→ Higher temperature,
higher activation.
However, when it is over
the the exist range, the
protein is natured and lost
the effect.

Table 3: Result and explanation for Team 1’s experiment

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Baseline 1st time 2nd time 3rd time

10
9 9.5
RATING SOUR INTENSITY

8 9 9 9 9
8.5 8.5
7 8 8
7.5
6 7 7 7 7 7 7 7 7 7

5 6

4 5

3
2 2.5
1 2
1
0
Acidic Basic Large Small High temperature Low Temperature
Concentration Concentration
EXPERIMENTAL CONDITION

Resulting for Team 2's experiment

This experiment determines the effect of above environmental factors to the activity of
Miracle fruit. The sample we use in this experiment is sour taste sample. However, we use
passion juice instead of lime, because passion stay at juice state so we and easy to perform
experiment; furthermore, the Essential Oil in the lime skin can make some bitter tastes, which
is considered to cause unwanted impacts to the result. This experiment will study the effect of
changing in pH, concentration and temperature of miracle fruit to its sweet-inducing process.
Based on some changes of the effect’s efficiency belong to the environmental factors, we can
guess the structure inside miracle fruit play as a vital role in this effect is a protein (Miraculin)
without analysis chemical structure of the fruit.

Comparison between practical result and learnt theory:

• Taste modifiers have the ability to alter one or more of the basic tastes. There are
many types of taste-modifying proteins like having sweet, anti-sweet and sweetness-
inducing abilities. However, in this experiment, only the effect of miracle fruit been
tested. In theory, miracle fruit can make sour food turn sweet and it does not alter the
taste of salt, spicy, umami and bitter. Moreover, when changing the concentration,
temperature and pH of the fruit, its effect will also change. To specific, the effect of
miracle fruit will be inactivated by increasing the temperature, reducing its
concentration and making the pH less than 7, while the effect of miracle fruit will be
risen by decreasing the temperature, increasing its concentration and making the pH
more than 7.xii. Because the main factor forming this effect of miracle fruit is
Miraculin, a protein so that, when some environmental changes can lead to the
changes of Miraculin structures so that the efficiency of the effects would be altered.
• In theory, the miracle fruit affect the taste of sour and make sour food become sweet
and the effect is washable. Besides, the effect can last from 15 minutes to 2 hours so
the effect, in theory, is washable in a longer term compared to the experiment design
so we can collect practical data for this situation. However, in some test, in the first

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time the effect is unclear or insignificantly, but later test is completely worked, this is
because there is not enough time for the miracle fruits to change the acid molecules or
structure into another form which makes it sweeter and less sour. The change of
concentration, pH and temperature can reduce or even inactivate its effect. However,
it has some factors may affect the miracle fruit’s ability like some people are
“supertasters” so they taste every kinds of food more sensitively than the others or the
place where those fruits were planted and gathered, these things are all needed to be
considered as well.
Moreover, there are some comments about the experimental design. We had designed the
protocol based on three principles above, however, we cannot control and balance the time to
test washability of the effect and how it lasts. Choosing random testers without any taste tests
leads to non-unified result. If we follow randomization rules, the number of testers is much
larger to have statistical significance. Basically, the result can only use to verify the previous
research or learnt knowledge that the miracle fruit can make the sour food taste sweet and this
effects can change belong to environmental factors (answer question 1 and 4 in clue-question
list), but not to explain further about the mechanism of the effects.
Overall, it is easy to see that at the first tasting time, miracle fruit has less effect then the
next tasting time. While, the effect seems to decrease in the third time. It can be explained that
Miraculin need significant time to be activated to optimal state, and its effect decreasing by the
washout of water or affects from the previous tests.

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IV. CONCLUSION:
From the practical result, we can conclude that:
- The miracle fruit has the ability to make sour food taste sweet and cannot change other
types of taste.
- The efficiency of this effect is altered belong to experimental factors, such as:
temperature, pH and concentration.
However, we also can show off something need to improve for the next experiment:
- In theory, this effect is washable for longer term compared to our experiment design so
we can collect significant washablity data.
- The result is subjective and there are not any realistic evidences to verify the result. The
quality of testers is not equal because the sense of taste of everyone is different due to
the number of taste cells and also the sensibility of these cells.

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Group 3 Monday Morning Biological Laboratory

CONTRIBUTION TABLE
Contribution
Name Work
percentage
Do Quoc Dat Find out and fill the “Result &
Discussion” part. Correct the 20%
mistakes
Trinh Phan Ngoc Khanh Identify the differences between
objects in the experiments and join
20%
with group to complete the report.
Correct the mistakes
Dai Quang Minh Fill the “Material & Experimental
design” part based on class 20%
experiment. Correct the mistakes
Le Minh Nguyen Sum up all things in the report,
design the cover and re-design the
report. Writing “Summary, 20%
Conclusion” part, and sketch the
graphs. Correct the mistakes
Bui Thi Nhu Quynh Find out and fill the Introduction
20%
part. Correct the mistakes

REFERENCES

i
David A.Yarmolinsky, Charles S.Zuker, Nicholas J.P.Ryba. Common Sense about Taste: From
Mammals to Insects. Cell, Volume 139, Issue 2 (2009), Pages 234-244.
https://www.sciencedirect.com/science/article/pii/S0092867409012495#bib48
ii
B. Lindemann. Receptors and transduction in taste. Nature, 413 (2001), pp. 219-225.
J. Chandrashekar, M.A. Hoon, N.J. Ryba, C.S.Zuker. The receptors and cells for mammalian
taste. Nature, 444 (2006), pp. 288-294.
iii
K.Ikeda. On a new seasoning. J. Tokyo Chem. Soc., 30 (1909), pp. 820-836.
iv
A.A. Bachmanov, G.K. Beauchamp, M.G.Tordoff. Voluntary consumption of NaCl, KCl, CaCl2, and
NH4Cl solutions by 28 mouse strains. Behav. Genet., 32 (2002), pp. 445-457.
B. Lindemann. Receptors and transduction in taste. Nature, 413 (2001), pp. 219-225.
v
Dr. Chris. Taste Buds (Human Tongue) and Sense of Taste (Sensation). 2018.
https://www.healthhype.com/taste-buds-on-the-human-tongue.html
vi
R.J. Delay, J.C. Kinnamon, S.D. Roper. Ultrastructure of mouse vallate taste buds: II. Cell types
and cell lineage. J. Comp. Neurol., 253 (1986), pp. 242-252.
J.C. Kinnamon, D.M. Henzler, S.M. Royer. HVEM ultrastructural analysis of mouse fungiform
taste buds, cell types, and associated synapses. Microsc. Res. Tech., 26 (1993), pp. 142-156.
B. Lindemann. Receptors and transduction in taste. Nature, 413 (2001), pp. 219-225.

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Group 3 Monday Morning Biological Laboratory

vii
Dr. Chris. Taste Buds (Human Tongue) and Sense of Taste (Sensation). 2018.
https://www.healthhype.com/taste-buds-on-the-human-tongue.html
viii
Melissa Petruzzello. Miracle fruit. Encyclopædia Britannica, inc (2018).
https://www.britannica.com/plant/miracle-fruit
Bob Yirka. Researchers uncover secrets of ‘miracle fruit’. (2011). https://phys.org/news/2011-
ix

09-uncover-secrets-miracle-fruit.html
x
Cagan RH. Chemostimulatory protein: a new type of taste stimulus. Science. 1973 Jul 6;
181(4094):32-5.
Kurihara Y. Characteristics of antisweet substances, sweet proteins, and sweetness-inducing
proteins. Crit Rev Food Sci Nutr. 1992; 32(3):231-52
xi
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protein, miraculin, from miracle fruit. J Biol Chem. 1988 Aug 15; 263(23):11536-9.
Theerasilp S, Hitotsuya H, Nakajo S, Nakaya K, Nakamura Y, Kurihara Y. Complete amino acid
sequence and structure characterization of the taste-modifying protein, miraculin. J Biol Chem.
1989 Apr 25; 264(12):6655-9.
Yamashita H, Theerasilp S, Aiuchi T, Nakaya K, Nakamura Y, Kurihara Y. Purification and
complete amino acid sequence of a new type of sweet protein taste-modifying activity, curculin.
J Biol Chem. 1990 Sep 15; 265(26):15770-5.
xii
Lipatova, O., & Campolattaro, M. M. (2016). The Miracle Fruit: An Undergraduate Laboratory
Exercise in Taste Sensation and Perception. Journal of undergraduate neuroscience education :
JUNE : a publication of FUN, Faculty for Undergraduate Neuroscience, 15(1), A56–A60.

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