THE EFFECTS OF DIFFERENT STORAGE TEMPERATURES ON THE
TASTE AND CHEMICAL COMPOSITION OF DIET COKE
BY JENNIFER COHEN
Jennifer Cohen is an eleven-year old student in Mrs. Simmons' sixth grade
Oradell, New Jersey class. The principal of Oradell Public School is
Scott Ryan. He may be reached at 201 261-1181. Jennifer conducted an
experiment proving aspartame, the artificial sweetener in diet soda, breaks
down into two deadly neurotoxins when stored at room temperature and under
ABSTRACT: The level of aspartame in a can of Diet Coke was found to be
0.06% by a food testing laboratory. The remaining cans from one case of
Diet coke were stored under three different heat conditions for 10 weeks.
Seven cans were stored in an incubator (104 degrees Fahrenheit), seven
cans were stored at room temperature (68-70 degrees Fahrenheit). At the
end of 70 days samples were tested for levels of aspartame, formaldehyde
and DKP (diketopiperazine). The refrigerated sample contained 0.058
percent aspartame, 0.001 percent DKP and 53.5 parts per billion of
formaldehyde. The room temperature sample contained 0.051 percent
aspartame, 0.002 percent DKP and 231 parts per billion of formaldehyde.
The incubator sample contained 0.026 percent aspartame, 0.010 percent DKP
and 76.2 parts per billion of formaldehyde. In addition 10 human subjects
tasted each soda sample plus a new can of Diet Coke and rated each sample
for taste on a 1-4 scale with 1 being the best and 4 being the worst. The
new can of Diet Coke received an average rating of 2.0. The sample stored
in the refrigerator received an average rating of 2.6. The sample stored
at room temperature received an average rating of 2.5. The sample stored
in the incubator received an average rating of 3.8. The effects of heat
on Diet coke produced the worst taste and the highest amount of loss of
aspartame as well as the greatest increase in levels of DKP. The most
pleasing taste was for the new can of Diet Coke. The room temperature
sample and the refrigerated sample scored almost the same in the taste
test. All samples revealed a presence of formaldehyde. However, the
highest level of formaldehyde occurred in the room temperature can.
There was also formaldehyde present in the refrigerated sample.
BACKGROUND: Aspartame was discovered in l965 by Searle chemist, Jim
Schlatter. He was developing this drug for another use and after
accidentally licking his finger found that aspartame was sweet. Today
aspartame is consumed by more than 100 million people in the United
States. This chemical (aspartame) has been approved by the Food and Drug
Administration (FDA) who said that an individual can safely consume 97
packets of aspartame every day. Aspartame is in many products including
some that children use such as diet soda, light yogurt, Flintstone
Vitamins, baked goods, puddings, and Winterfresh gum. It has been known
to cause headaches, nausea, vision problems, seizures and cancer in its
The ingredients in aspartame are aspartic acid, phenylalanine, and methyl
alcohol. Methyl alcohol is a chemical that breaks down in high
temperatures and turns into formaldehyde and DKP (diketopiperazine), two
chemicals known to cause problems in the nervous system. Aspartame's life
is 262 days at 77 degrees Fahrenheit, or 25 degrees Celsius. The FDA gets
more complaints about aspartame than any other food or drink. The
symptoms of aspartame are a lot like the symptoms of multiple sclerosis
and Alzheimer's disease. Ever since aspartame was approved in l985, there
has been an increase in brain tumors. There is no direct proof that
aspartame caused the brain tumors, but there is enough reason to suspect
that, and the television show, "60 Minutes" recently did a report linking
the increase in brain cancer to aspartame use.
The FDA reviewed Searle's studies of this artificial sweetener in which
rats were fed aspartame daily with their meals for one year. There were
12 brain tumors in the 320 rats that were fed aspartame and no brain
tumors in the 120 rats that were not fed aspartame.
There was also a study done at the University of Wisconsin on rhesus
monkeys. they were fed aspartame daily. After day 200 of a one year
study the monkeys developed epileptic seizures. After the study ended,
the aspartame was discontinued and the monkeys were fully watched for
60 days. The monkeys had no more seizures.
METHOD: I did my own experiment on aspartame. On January 21, l997, I
bought a new case of Diet Coke from the supermarket. I put 7 cans in the
refrigerator, 7 cans in my room at room temperature (about 69 degrees) and
I put 7 cans in a BOEKEL incubator (80 Watts, 120 AC volts, 0.75 Amps,
catalog # 131500) and set the temperature at 40 degrees Celsius which is
104 degrees Fahrenheit. I left them in there for 10 weeks (70 days). I
had a thermometer next to each group of cans and I checked the
temperatures daily. I took the remaining three cans and brought them to
Winston Laboratories in Ridgefield, New jersey to test for a beginning
level of aspartame. When I got the test results back, they revealed that
there was normally 0.06 per cent of aspartame in the can of diet soda.
I chose that temperature because in l985 the National Soft Drink
Association reported a similar experiment in which diet soda stored at
that temperature turned into formaldehyde. In that experiment they
explained that 104 degrees Fahrenheit was equal to a daytime temperature
in Phoenix, Arizona over the summer. The National Soft Drink Association
recommended that aspartame not be approved for use by people in soda.
They published this experiment and their recommendation in the
On April 1, I took the cans of aspartame out of the refrigerator, out of
my room and out of the incubator. That day I brought the samples to
Winston Laboratory for analysis.
I was going to do a taste in my sister's fourth grade class, but the
school nurse said that I couldn't because of all the bad things people say
about aspartame, so instead I tested the samples on a group of adults.
I performed a double blind experiment. My mother helped to label each
sample with a number. I conducted the experiment but I did not know which
sample each person was drinking. I put all of the cans in a cooler and
covered them with ice sos that they would be served at the same
temperature. I gave each person a small cup of the soda from the
refrigerator, from the incubator, from my room, and from a new can of soda
fresh from the supermarket. I asked them to rate the taste on a scale of
one to four, four being the worst and one being the best. The actual
results are to be found in table#1.
See this in Pamphlet format,
Table #2 contains the results of the testing conducted on the samples
analyzed by Winston Laboratories. In the sample that was in the
refrigerator all that was left of the 0.06 per cent of the aspartame was
0.058 percent. That extra aspartame had turned into 0.001 percent DKP and
53.5 parts per billion of formaldehyde In the sample from my room, all
that was left of the 0.06 percent aspartame was 0.051 per cent. The extra
aspartame had turned into 0.002 percent DKP and 231 parts per billion of
formaldehyde. In the sample that was in the incubator all that was left
of the 0.06 percent aspartame was 0.026 percent. The extra aspartame had
turned into 0.010 percent DkP and 76.2 parts per billion in the
ROOM COLD WARM NEW
TEMP. STORAGE STORAGE CAN
SAMPLE SAMPLE SAMPLE SAMPLE
#517 #502 #540 #563
SUBJECT #1 4 4 4 3
SUBJECT #2 3 2 4 1
SUBJECT #3 2 3 3 2
SUBJECT #4 1 2 4 2
SUBJECT #5 2 2 4 1
SUBJECT #6 2 3 4 1
SUBJECT #7 2 3 3 4
SUBJECT #8 3 2 4 3
SUBJECT #9 3 2 4 1
SUBJECT #10 3 3 4 2
AVERAGE 2.5 2.6 3.8 2.0
DISCUSSION: There was an obvious preference for the newly purchased
sample of Diet Coke. The scores for the sample in the refrigerator and
room temperature were similar but were not as high as the new soda. The
score for the incubator sample were very low. Nearly everybody hated the
There are taste differences. Ten people preferred the new soda to the
other three samples. With 1 being the best and 4 being the worst, their
average score for the new soda was 2.0.
The aspartame contained in diet soda stored over time can break down into
formaldehyde and DKP, two very dangerous poisons. Taste tests revealed a
noticeable difference among tasters. The higher the heat of storage, the
worse the taste.
Diet soda stored for ten weeks loses flavor. Aspartame in that soda
breaks down into two products, formaldehyde and DKP. The warmer the
temperature, the greater the loss of aspartame and the greater the
increase in DKP.
Temperature creates two effects. First, the higher the temperature of
storage, the higher the level of DKP in the soda. Second, room
temperature seems to create the highest levels of formaldehyde in soda.
At very high temperatures, the formaldehyde breaks down. However, even
stored in a refrigerator at cold temperature, the aspartame breaks down
After diet soda containing aspartame is purchased it should not be stored
in the heat or under any condition for a long period of time. Further
research should be performed with more samples at different temperatures
for different time periods so that safety levels can be determined.
Concerning aspartame, the FDA says, "we believe that based on all the
information that we received to date that this is a safe product." I
say, "Decide for yourself." Jennifer Cohen
ASPARTAME DKP FORMALDEHYDE
% % Parts per billion
BASELINE CAN 0.060% * *
SAMPLE # 502 0.058% 0.001% 53.5
SAMPLE # 517 0.051% 0.002% 231.0
SAMPLE #540 0.026% 0.010% 76.2
SAMPLE # 563 * * *
* Sample #563 (new can of Diet Coke was not tested by the lab. It was
used for the taste test only. The baseline can was not tested for
formaldehyde or DKP because it was assumed that FDA would ban any new
product containing poison. The total cost of testing was $1250. This
may not be a lot of money to a drug company but it is to me. As it is,
I will be baby-sitting for the summer of 1997 to pay for this study. -JC
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or download a copy in Wordperfect format.