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The science of popcorn |
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Informations |
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Project:
The science of popcorn |
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Developed By:
Marie-Christine Gosselin |
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Type of Project:
Experiment |
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Category:
Physical science |
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Class:
Senior 1 |
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Age of Participant:
16 |
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School:
Montcalm |
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Teacher:
Claude Vallée |
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Has Won:
Silver medal for a
physical science project |
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Project presented at the 1998 Eastern Townships
regional final of the Bell Science Fair
Selected for the 1998 Quebec final (Montreal) of the Bell Super Science
Fair
Selected for the 1998 Pan-Canadian Science Fair in Timmins, where the
participant won
a silver medal for a physical science project, senior level
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Introduction |
Like most people, we love popcorn, especially with
tons of melted butter. Of course, the greasy feeling left on our fingers
afterwards is pretty unpleasant and is particularly inconvenient at the
theatre. We gave some serious thought to the problem and, as a result,
our project focuses on the search for a solution that would make it possible
to produce flavoured, non-greasy popcorn. Our project was carried out
in several stages, which we have grouped into four main experiments described
in this report.
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Development |
General objective: To produce butter-flavoured popcorn
that is not greasy to the touch, while preserving the usual shape and
texture.
General materials: popcorn, balance, jars, beakers (50 mL, 100
mL, 1 L), popcorn popper, strainer
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Specific materials: |
Experiment
1
butter concentrate
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Experiment
2
vacuum pump and bell jar
graduated cylinders (10 mL and 2 L)
calorimeter
hot plate
thermometers
bag sealer
grinder
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Experiment
3
butter concentrate
oven
thermometer
fan |
Experiment
4
vacuum pump and bell jar
butter concentrate
oven
thermometer |
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Experiment 1: Giving popcorn kernels their
flavour |
Objective: To give popcorn kernels a buttery flavour.
Principle: Two environments containing different concentrations of flavoured
solution are separated by a permeable membrane. The high-concentration
solution in one environment is diffused to the environment containing
the low-concentration solution.
Hypothesis: We believe that soaking the popcorn kernels in a flavoured
solution will allow the flavour to be diffused to the kernels.
Protocol:
| 1. |
Prepare various concentrations of butter solution (5, 10, 15 drops per 30 mL). |
| 2. |
Place 15 g of popcorn kernels in each solution. |
| 3. |
Wait approximately 12 hours and drain the kernels. Spread them out for 30 minutes and let dry. |
| 4. |
Pop the kernels and record any observations. |
Observations
and analysis of results
Following the noisy popping of the kernels, we observed that they
were smaller than usual, shrivelled and had a rubbery texture. Also,
water vapour was being released from the popcorn popper. During the popping,
we noticed that the first kernels were generally smaller than the last.
Furthermore, unlike what we first thought, the popcorn took on only a
very subtle flavour. The flavour intensity was, however, proportional
to the concentration of the soaking solution.
Suggestions
We would have to redo the experiment with higher concentrations
of solution, since they were probably not high enough. Moreover, we could
probably improve our method by doing more in-depth research on the factors
that influence the popping of the kernels, as well as an evaluation of
the popped kernels.
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Experiment 2: Properties of popcorn |
Objective: To validate our experimental method by
relying on the experiment report written by Robert G. Hunt and establishing
the main properties of popcorn.
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Experiment 2a: |
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Relative humidity of unpopped kernels |
Principle:
Water evaporates much more readily in a dehumidified environment
at very low pressure, as is the case in a vacuum pump.
Protocol:
| 1. |
Place 30g of ground popcorn inside an empty bell jar. |
| 2. |
Activate the vacuum pump for approximately three days, taking
care to mix the kernels and record their mass several times. |
| 3. |
Stop the pump once the mass is stabilized. |
Observations
and analysis of results:
After three days of dehydration, we observed a difference in mass equal
to a level of humidity of 11.33%. This value compares with that obtained
by Robert: around 12%. Our method was therefore effective.
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Experiment 2b: |
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Popping temperature |
Principle:
The temperature inside the popping chamber is comparable to the
temperature inside the kernel.
Protocol:
| 1. |
Install a thermometer in the popcorn popper. |
| 2. |
Record the temperature during popping. |
| 3. |
Repeat Steps 1 and 2 several times with kernels of varying degrees
of humidity. |
N.B. We also conducted the previous
experiment using vegetable oil. The results were similar.
Observations
and analysis of results:
Not all the kernels pop at the same temperature. For a given degree
of humidity, the higher the temperature, the larger the popped kernels.
The variation in popping temperature created by the initial degree of
humidity is negligible.
The average popping temperature is 187.64°C, which, once again,
is comparable to Robert’s result of 175°C.
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Experiment
2c: |
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Specific heat |
Principle:
- In a heterogeneous mixture, the temperature is constant for each
component.
- During heat transfer, the energy will be conserved if the system
is insulated.
Protocol:
| 1. |
Place 100 g of popcorn kernels in the strainer and submerge in
boiling water for five minutes. Record the temperature of the water. |
| 2. |
During this time, place 150 g of water in the calorimeter and
record the temperature. |
| 3. |
Very quickly, drain the kernels and insulate them in the calorimeter. |
| 4. |
Record the highest temperature. |
Observations
and analysis of results:
Following our calculations, we obtained a specific heat of 3.04 J/g°C.
This is quite different from the result obtained by Robert, that is,
1.51 J/g°C. We do, however, have reason to believe that our value
is more representative, because our system was almost perfectly insulated
and our only possible source of error was a loss of energy during the
draining of the kernels.
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Experiment 2d: |
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Mass and volume |
Objective:
To measure the mass and volume of the popcorn kernels before and
after popping in order to calculate the expansion and volumetric mass
for different degrees of humidity.
Scenario:
We simply used a balance to determine the mass of the kernels. For the
initial volume, we used water displacement, although this was far more
difficult for the final volume.
Problem:
Using water displacement to measure the volume of the popped kernels
was, in fact, impossible. The popcorn simply absorbed the water. We needed
to find a more appropriate method.
Solution:
We would have to seal the popped kernels in bags from which the
air had been removed. We could then measure the volume using water displacement,
taking into account the volume of the bag itself.
Overall
protocol:
| 1. |
Pop the kernels. |
| 2. |
Break up the kernels into little pieces and place them in the
bag. |
| 3. |
Insert the vacuum pump hose into the bag, squeezing the kernels
together with the other hand. |
| 4. |
Activate the pump until a vacuum is achieved. Seal the bag. |
| 5. |
Measure the volume using water displacement. |
N.B. This experiment was repeated several
times. The details regarding the initial quantities used are not mentioned
in this overall protocol since they varied.
Observations
and analysis of results:
Measuring the volume was a difficult operation. We could easily
see that the kernels that were either too humid or not humid enough at
the outset were smaller after popping. The results obtained did not,
however, prove this conclusively. The best explanation for this phenomenon
is undoubtedly the lack of precise instruments. Moreover, we did not
entirely succeed in creating a vacuum inside the bag. We did, however,
manage to achieve our objective, which was to calculate the expansion
and volumetric mass of the kernels with respect to the level of humidity.
We can state that, in general, for a given initial mass of popcorn, the
expansion decreases when the kernels are dehydrated. Conversely, the
expansion reaches its maximum when the humidity is normal, that is, between
11% and 12%. As for the volumetric mass, the tendency seems to be that
the dryer the kernels are initially, the denser they are.
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Experiment 3:
Drying the flavoured kernels |
Scenario:
We now know that kernels that have soaked in a flavoured solution
are too humid to pop normally. We also know that the concentrations of
solution used in experiment 1 were too weak.
Objective:
To find a way to restore an appropriate humidity to the kernels,
while improving their flavour.
Analysis
of results:
We concluded that drying the kernels before popping produced popcorn
whose shape, texture and size approached the desired results, although
there was still room for improvement. Our observations also revealed
that the oven drying method was more effective, provided the temperature
was not too high.
Suggestions:
Since the concentration of flavoured solution was already relatively
high, we suggested developing a method of increasing the kernels’ absorption
of flavour.
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Experiment 4:
Sponge effect |
Scenario:
The kernels did not have much butter flavour, even when we increased
the concentration of the soaking solution.
Objective:
To increase the kernels’ absorption of flavour.
Hypothesis:
Lowering the popcorn kernels’ level of humidity before soaking
could increase their ability to absorb the flavoured solution.
Method
1:
Fan
Using a fan to dry the kernels would help restore the desired
humidity. |
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Method
2:
Oven
Using an oven to dry the kernels would help restore the
desired humidity. |
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Protocol:
Prepare different concentrations (30, 45, 60 drops/30
mL) of butter-flavoured solution. Place 15 g of kernels in each
solution and wait 12 hours. Drain the kernels, place in a beaker
and, depending on the case, place under a fan or in an oven. Pop
the kernels after several hours. |
Observations:
Compared with experiment 1, the shape and texture of
the popcorn improved. The flavour is more pronounced, but
still rather subtle. |
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Observations:
Similar results, with some improvement |
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Protocol:
| 1. |
Place 15 g of popcorn kernels in the bell jar and activate
the vacuum pump for 36 hours. |
| 2. |
Remove the kernels and let soak for four hours in a butter-flavoured
solution with a concentration of 60 drops/30 mL. |
| 3. |
Drain the kernels and dry in an oven until they reach their initial
mass. |
| 4. |
Pop the kernels and record any observations. |
Observations
and analysis of results:
We observed a definite improvement in taste. This last product was
more satisfactory. As for the shape, size and texture, the results remain
quite conclusive so far. We concluded that, with this method (which makes
it possible to verify the humidity of the kernels, while maximizing the
flavour absorption), we managed to produce the desired popcorn.
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Conclusion |
We feel that we achieved the general objective of
this project, which was to produce butter-flavoured popcorn that was
not greasy to the touch. After much testing and questioning, we managed
to obtain the desired popcorn. Our methods could definitely be improved
and lead to even more conclusive results. We do, however, consider our
results acceptable. We are currently testing various other flavours.
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© 2002, Conseil de développement du loisir scientifique (CDLS). This
document is distributed by the Conseil de développement du loisir scientifique.
For more information, visit our Web site at www.cdls.qc.ca. |
The opinions expressed
in this section are those of the authors and do not necessarily
reflect the opinions of Merck Frosst or its employees. |
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Objective: To give popcorn kernels a buttery flavour.
