Yeast and fermentation: four different sugars
Karlijn Hasaart en Esmée de Looff
Summary
On the occasion of the experiment which is performed by Slaa et al. (2009); Yeast
and Fermentation: the optimal temperature, we performed a following experiment by
ourselves with the inquiry question: Is the kind of sugar determinative for the release
of a higher measure of ethanol? If so, which sugar releases the most ethanol?
We researched the different productions of ethanol and carbon dioxide by using four
different kind of sugars; glucose, cane sugar, fruit sugar and malt sugar. First of all
we put the solutions of the different sugars with water and yeast by a temperature of
25 degrees (298 K) for about two days. And then we put all the solutions in a warmth
bath of 37 degrees (310 K). After three days we came back and we were able to
conclude something we didn’t expect.
Introduction
Slaa et al. (2009) did their experiment
based on the fact that oil resources will
be exhausted. This knowledge
stimulated Slaa et al.’s interest in one
of mankind’s oldest chemical
processes: the production of bioethanol from sugars by fermentation. In
stead of the temperature as a
independent variable, we took the
different kind of sugars as a
independent variable. We used
glucose, cane sugar, fruit sugar and
malt sugar for our experiment. The
molecular formulas of these sugars
and their fermentation equations are:
- C6H12O6 (glucose)
C6H12O6
 2 CH3CH2OH (l) + 2 CO2 (g)
- C6H12O6 (fruit sugar) C6H12O6
 2 CH3CH2OH (l) + 2 CO2 (g)
- C12H22O11 (cane sugar)
C12H22O11  4 CH3CH2OH
(l) + 4 CO2 (g)
- C12H22O11 (malt sugar)
C12H22O11  4 CH3CH2OH
(l) + 4 CO2 (g)
So our question to be answered will
be: Is the kind of sugar determinative
for the release of a higher measure of
ethanol? If so, which sugar releases
the most ethanol?
With the four different equations, we
can calculate the different masses of
the released ethanol and carbon
dioxide.
On the occasion of the equations of the
fermentation of the four sugars we can
almost conclude that the biggest mass
of ethanol and carbon dioxide will be
produced by cane sugar or malt sugar.
Out of the proportion between the
sugars and the equation products we
can see that glucose and fruit sugar fits
twice in cane sugar and malt sugar.
These two sugars have a proportion of
1:4 with their equation products. But
before we can make our complete
hypothesis, we also need to know the
different kind of properties of the two
different kind of sugars;
On the internet we discovered that
every organism is able to break off
malt sugar. And yeast is a Fungi, so it
counts as an organism. Cane sugar is
sugar made from cane but doesn’t
really carry an extraordinary property.
So out of this information we can form
our hypothesis; malt sugar will release
the biggest mass of ethanol and
carbon dioxide.
Experimental procedure and
approach
First of all we needed to calculate how
much we needed of the four different
sugars. We took 0,1 mol of fruit sugar
and glucose and we calculated the
mass of both of the sugars by
multiplying the mol with the molar
mass (180,2 * 0,1 = 18,02 gram fruit
sugar and glucose). For cane sugar
and malt sugar we used 0,05 mol for
each, that’s because the molar
proportion of C6H12O6 and
C12H22O11. So by multiplying the mol
cane sugar and malt sugar with the
molar mass we can calculate the
mass: 342,3 * 0,05 = 17,12 gram cane
sugar and malt sugar. But malt sugar is
only available in syrupy fluid, which
contains 74 gram malt sugar in 100
gram syrupy fluid.
Mass syrupy fluid
Mass malt sugar
100,0
gram
74,00
gram
-
23,14
1,000
17,12
Then we weighed the needed quantity
of the sugars. But before we put the
sugar in the conic flasks, we weighed
the conic flasks one by one (because
not every conic flask has the same
mass). So when we put the sugar in
the conic flask, we filled the conic flask
with 100 mL demiwater, which we
measured earlier before with a
measuring cylinder. We used a
measuring cylinder because it is the
most accurate way of measuring. Now
the solution was made, we needed the
yeast to complete the experimental
solution. We took for each conic flask
1,5 gram yeast and we added the
yeast to the solution. Then we weighed
the conic flasks with the sugar-solution
and the yeast.
Apart from the fermentation
experiment, we weighed an extra conic
flask, and filled it with also 100 mL
(weighed) demiwater to calculate the
evaporated H2O. Because in the
sugar-solutions the added demiwater
can also be evaporated.
This whole trial is done twice because
we do a duplicate determination to be
sure the data is reliable.
After we make the solutions, we put
the conic flasks by a temperature of 25
degrees (298 K) for about two days.
We did this because we wanted to
check Slaa et al.’s data. When we
came back after two days we found out
their data is reliable because the yeast
cells didn’t ferment at all.
After we found out, we put all the conic
flasks in a warmth bath of 37 degrees
for three days.
At last, when we get all the conic flasks
out of the warmth bath, we weighed
them again.
The extra conic flasks we used during
the whole experiment showed us after
the whole process how much
demiwater is evaporated during the
whole experiment. We can calculate
this by subtract the ‘new’ mass from
the ‘old’ mass.
Results
Three days after the morning we put
the conic flasks in the warmth bath,
we came back to weigh all the
solutions. The smell was a very heavy
smell of alcohol, some sort of strong
beer-scent.
Table 1, 2 and 3 present - in duplicate the mass of the solution before the
beginning of the experiment, the
values of the solutions after they were
placed at 25 degrees and the values of
the solutions when they got out of the
bath.
Table 1
Sugar
Glucose
Cane sugar
Fruit sugar
Malt sugar
Demiwater
Before bath
Measurement1
Measurement2
before bath
before bath
248,34 gram
250,07 gram
251,92 gram
240,14 gram
255,66 gram
245,27 gram
251,76 gram
258,74 gram
225,86 gram
232,48 gram
Table 2
25 degrees (298 K)
Sugar
Glucose
Cane sugar
Fruit sugar
Malt sugar
Demiwater
Table 3
Sugar
Glucose
Cane sugar
Fruit sugar
Malt sugar
Demiwater
Measurement1
Measurement2
25 degrees (298 K)
25 degrees (298 K)
246,17 gram
247,81 gram
248,45 gram
235,91 gram
253,40 gram
243,14 gram
246,40 gram
253,91 gram
221,45 gram
227,98 gram
37 degrees (310 K)
Measurement1
Measurement2
37 degrees (310 K)
37 degrees (310 K)
234,28 gram
237,06 gram
246,09 gram
234,95 gram
244,05 gram
234,09 gram
246,00 gram
252,19 gram
225,35 gram
231,78 gram
Table 4 and 5 (beside) show how
much water is evaporated and how
much ethanol is produced by the
fermentation of measurement 1 and
measurement 2.
Table 4
Sugar
Glucose
Cane
sugar
Fruit
sugar
Malt sugar
Demiwater
14
Evaporated
water
0,51 gram
11,61
gram
0,51 gram
11,10
gram
5,76
gram
0,51
gram
0,51 gram
5,25
gram
-
Weight
loss
13,01
gram
5,19
gram
Evaporated
water
0,70 gram
11,18
gram
0,70 gram
10,48
gram
6,55
gram
0,70
gram
0,70 gram
5,58
gram
-
Sugar
Glucose
Cane
sugar
Fruit
sugar
Malt sugar
Measurement 2
12
Measurement 2
8
6
4
2
0
Glucose
Fruit
sugar
0,51 gram
Table 5
Measurement 1
10
0,51 gram
Released
ethanol
13,55
gram
5,32
gram
Measurement 1
Demiwater
Figure 1 (below) shows in duplicate the
bar plot of the ethanol which is
released by the different sugars.
Weight
loss
14,06
gram
5,38
gram
0,70 gram
0,70 gram
Released
ethanol
12,31
gram
4,49
gram
Data analysis
The mass of the released ethanol of
one measurement is calculated by the
following formulas:
mass demiwater before warmth bath –
mass demiwater after water bath =
evaporated water
mass solution before warmth bath –
mass solution after warmth bath =
weight loss solution
weight loss solution – evaporated
water = produced ethanol
Discussion and conclusion
It’s obvious that the biggest mass of
ethanol is produced by the
fermentation of glucose as you can see
in the bar plot of the released ethanol.
As you can see in table 2, glucose
performed the biggest loss of weight
during the experiment. So during the
fermentation, glucose was able to
produce a lot of ethanol. The average
weight of the produced ethanol is
12,39 gram. On the occasion of this
conclusion, we can say that our
hypothesis is wrong. We thought that
malt sugar would release the most
ethanol with it’s fermentation. But we
didn’t notice that it’s possible that the
syrupy malt sugar contains
components with inhibitory function.
Evaluation
The experiment expired very well, we
kept every conic flasks with it’s solution
under the same circumstances during
the whole experiment. So the variables
were kept the same the whole time.
Only the kind of sugar was changed;
out independent variable to inquire if
the kind of sugar is determinative to
the mass of the released ethanol.
Everything was easy to retrieve and
kept at a safe place. So the set up was
suitable enough to achieve the answer
to our inquiry question.
An improvement can be that we heat
the sugars to their boilingpoint, and
liquefy the sugar and the water under a
As an example we use the values of
the fruit sugar from measurement 1 to
show what we exactly did:
225,86 – 225,35 = 0,51 gram
evaporated water
255,66 – 244,05 = 11,61 gram weight
loss of the solution
11,61 – 0,51 = 11,1 gram produced
ethanol
high temperature; the boiling point. The
boiling point is different for every sugar
so the sugar will be heated to it’s own
boiling point to make the solution with
water. There is a chance that the
released ethanol will be different from
the released ethanol when the sugar
isn’t warmed. So that could be the
customized independent variable.
Bibliography
1. http://translate.google.nl/
2. http://nl.wikipedia.org/wiki/Gist
3. http://nl.wikipedia.org/wiki/Malto
se