Ethical question: do we waste our resources?
The comparison of fermentation with beetroot juice and the fermentation with the leftover pulp of
beetroots
12-04-2010
Ashika Baan, Sharina Ibrahim
Summary
The production of bio-ethanol is a process that keeps lots of people busy nowadays. To be able to
improve the process of obtaining bio-ethanol from an organic product by fermentation, one has to
keep searching for better ways that are environmentally friendly and cheaper. In this inquiry
beetroots were used as organic matter to obtain the bio-ethanol from due to the fact that they
contain a high amount of glucose. Usually to obtain bio-ethanol from an organic matter like
beetroot or sugar beet, one first obtains the juice from the beet and then adds yeast to let the
fermentation go into process. The fermentation of this inquiry was carried out at a constant
temperature of 33° C by measuring the release of carbon dioxide.
Introduction
Ethanol is an important product for our
society. It is used as a bio-fuel in modern
transport and liquor consists for a big part of
ethanol. The synthetic production of ethanol
is done by reacting ethane, obtained from
crude oils, with water. Because crude oils are
exhausted by big oil companies like Shell, the
fermentation process with organic materials is
environmentally-friendlier and thus an overall
better way to obtain ethanol. The
carbohydrates are used as a begin-product for
fermentation. Sugar is a part of the
carbohydrates and organic materials that have
a high sugar-level are often used in the
fermentation process.
A fermentation process consists of glucose,
which is converted to ethanol and carbon
dioxide by yeast. This process is anaerobic. If
it would be done in a oxygen-rich
environment, then the glucose would react
with the oxygen to carbon dioxide and water
and then the ethanol would oxidize and the
products would be water and carbon dioxide.
But in this experiment it was done
anaerobically because the amount of carbon
dioxide, which is the same amount of
produced amount of ethanol can be measured.
If it would have been done aerobically, the
carbon dioxide would have oxidized and the
ethanol too.
The fermentation of glucose:
C6H12O6(s) → 2CH3CH2OH (l) + 2CO2 (g)
The goal in this inquiry was to see if the pulp,
which is usually thrown away, contains
glucose and if the amount of glucose in the
pulp was higher, lower or equal to the amount
of glucose in the juice. It is expected that the
pulp of a beetroot contains less carbohydrates
than the juice of the beetroot because nearly
all the sugar is expected to remain in the fluid
part of the beetroot (i.e. the juice) and not in
the flesh of the root (i.e. the pulp)
Experiment procedure and
approach
20 grams of pulp and 20 grams of juice are
weighed out precisely and put each in a
different bottle. 100 mL of distilled water is
put in each bottle. Two water bottles were
filled with water completely to the top. They
serve as carbon dioxide-capturers. Then 0,40
grams of yeast was added to the bottles with
the beetroot-extracts and an airtight cork with
a worm to conduct the carbon dioxide to the
bottles that capture the carbon dioxide was
put on the bottle with the solutions. The bottle
with the solution was placed in a bath with
Ethical question: do we waste our resources?
Juice
( quantity of
CO2 in mol)
Pulp
(quantity of
CO2 in mol)
Measurement 1
4,16
6,07
Measurement 2
3,36
5,80
Figure 2: The setup of the experiment
Measurement 3
3,49
5,80
water at a temperature of 33° C. The setup
stayed in the bath for two days. After two
days the bottles that captured the carbon
dioxide were weighed and the difference in
masses within each set of bottles after and
before fermentation were calculated by
subtracting the amount before and after. The
setup is presented as figure 2.
The results are presented graphically in the
following figures.
Table 2: release of CO2 in mol
The values displayed in Table 2 were
calculated by dividing all the values of Table
1 by 44,01, which is the molar mass of carbon
dioxide. Table 2 thus represents all the
quantities of carbon dioxide in the chemical
unit: mol. It is a better way to display the
quantities because the amount of produced
carbon dioxide is equal to the amount of
produced ethanol.
Results
Data analysis
7
6
Juice
( quantity of
CO2 in g)
Pulp
(quantity of
CO2 in g)
Measurement 1
183,27
267,23
2
Measurement 2
147,78
255,09
0
Measurement 3
153,75
255,38
Table 1: release of CO2 in grams
The values displayed in Table 1 were
calculated by subtracting the mass of the
water-bottle with the captured carbon dioxide
from the mass of the water bottle before the
fermentation took place. This was done by
weighing the bottles before and after the
fermentation with a very accurate weighingscale.
Ashika Baan, Sharina Ibrahim
5
mol
4
Juice
3
Pulp
1
Measurement 1 Measurement 2 Measurement 3
Figure 1: the results of the release of carbon
dioxide in mol
Conclusion and discussion
During the observations it was clear that
carbon dioxide was arising and that it was
conducted to the bottle. This is of course the
carbon dioxide-gas that was produced by the
yeast cells. A conclusion can be taken that the
cells were active and that the glucose in the
beetroots was converted to ethanol and carbon
dioxide in equal amounts.
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Ethical question: do we waste our resources?
The results from Figure 1 show that the
amount of released carbon dioxide gas of the
pulp is bigger than the amount of released
carbon dioxide-gas of the juice. One can
deduce that the pulp, which is thrown away in
factories, there usually is a high amount of
glucose that can be converted to ethanol. The
factories don’t use their resources properly if
they throw the pulp away. The bigger amount
of carbon dioxide produced by the pulp can
be explained because the degree of
distribution is bigger and the reaction can be
passed easier. According to the “colliding
particles-model” the bigger the surface, the
more space to collide and thus more chance
for the reaction to take place. The yeast could
easily react with the glucose from the
beetroot. The colliding particles-model also
embraces that when the concentration is
higher, the chance of effective collisions also
increases. The concentration of the beetroot
juice-solution could be lower than the degree
of distribution of the pulp (the degree of
distribution is the concentration for a solid
matter). The amount of glucose in the pulp is
bigger than the amount of glucose in the
juice. Due to this assumption the hypothesis
can be rejected, because it was assumed that
the concentration of the pulp would be lower
than that of the juice.
Evaluation
During our inquiry all the experiments were
performed as accurate as possible. The
dependant and independent variables were
kept constant as much as possible. Though it
can be assumed that some things were not
very accurate. The juice of the beetroot
became thick and slimy after three days, it
was nearly impossible to weigh it precisely.
Despite this fact the juice was still used for
the experiment. This could’ve had a bad
influence on the results. The thickened juice
couldn’t dissolve very easily in water and that
could’ve had an effect on the reaction and the
amount of the produced carbon dioxide and
ethanol.
The control-variables also have a significant
role in the inaccuracy of the experiment. The
bottles which captured the carbon dioxide
Ashika Baan, Sharina Ibrahim
were sealed with a cap after the fermentation
process. This had to happen under water and
it is possible that some carbon dioxide gas
escaped. This also makes sire that the results
aren’t hundred percent accurate. To improve
the degree of accuracy, fresh juice and pulp
could be used each time a measurement was
taken. That makes sure every measurement is
pure, but it also complicates the matter,
because different beetroots have to be used
and they may carry different gens or have
mutations We can conclude that we (as a team
doing this inquiry) For a follow-up study one
could inquire if the peel of the beetroot
contains more or less glucose and if it can be
missed because the peel usually contains the
most impurities and mutations.
Bibliography
1. http://nl.wikipedia.org/wiki/Ethanol
2. http://nl.wikipedia.org/wiki/Rode_biet
3. http://www.voedingswaardetabel.nl/vo
edingswaarde/voedingsmiddel/?id=79
9
4. http://www.suikerinfo.nl/allesoversuik
er/van_biet_tot_suiker.html
5. http://www.twanetwerk.nl/default.ashx
?DocumentId=2213
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