Dr. Oetker versus Fleischmann’s
Philip Habig & Gianpaolo Gioia
9 may 2010
Fermentation:
With this fermentation process, the sugars that we use D-glucose will be converted into carbon
dioxide and ethanol. This, carried out in an aerobic environment, by using bakers yeast.
The point of this whole process, is to try and find new ways to gain energy. By using this process,
ethanol (and carbon dioxide) is produced, and that is the source of energy that we are looking for.
Now, there are of course a lot of uncertainties, that’s why these experiments are necessary; to find
the most productive way of gaining energy from the fermentation process.
Inquiry question:
What is the influence of the kind of yeast, on the amount of carbon dioxide that is produced in the
fermentation process?
Dependant & independent variables:
Dependant variable: the amount of carbon dioxide (CO²) produced
Independent variables: the amount of bakers yeast used in the fermentation process
Hypothesis:
During the experiment, we will use three different types of yeast. The bakers yeast used in the
experiment by Slaa et al. (2009) and two other types of yeast.
We expect that the more aggressive/ effective the yeast is that is used, the faster the chemical
reactions will be, and therefore, the more carbon dioxide will be produced.
We base this hypothesis on the theory of the reaction surface. If the reaction surface is bigger, there
will be more chemical reactions by the molecules, and therefore more successful fusions by the
molecules. Based on this theory, we expect that more carbon dioxide will be produced when we use
a more aggressive type of yeast.
Furthermore we can only guess which is better based on what is written on the packages. And based
on the packages we say that Fleischmann’s yeast will be better. And therefore will produce more CO2
gas in two days.
Workplan
Control variables:
The variables that will have to be kept constant.
 The temperature in °C
 The concentration of D-glucose used
 The amount of D-glucose used
 The materials used
 The set up of the experiment
Materials list:
 A bath with water in which a constant temperature can be kept (33°C)
 0,25M D-glucose solution
 2 types yeast
o Bakers-yeast ( Gist Levure, instant, Dr. Oetker )
o Super-yeast, ( Active Dry yeast, all natural, Fleischmann’s )
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0,5l bottles (3x)
Test tubes (3x)
Distilled water
Rubber bands (3x)
Rubber hoses (3x)
Cups (3x)
Corks with holes (3x)
Taps (3x with hole & 3x without hole)
A scale
A pipette
Recipe:
1. Fill up three 0,5l bottles with distilled water.
2. Weigh the bottles (with taps without a hole in it).
3. Put the bottles in the water upside down and replace the caps for caps with a hole in it.
4. Now fasten the bottles to the shelf right above the water with rubber bands.
5. Take three clean tubes.
6. Fill the tubes with 25ml 0,25M solution of D-glucose (use the pipette for this).
7. Put the tubes in a rack and let it stand in the water.
8. Weigh off three cups with 0,20g yeast.
9. Now take three corks with little holes in it and three rubber hoses.
10. First put the rubber hoses into the bottles of water through the caps with the holes in it.
11. Put the other end of the rubber hoses through the corks.
(Steps 12 and 13 should be performed in quick succession, so that an more accurate test is
performed, and steps should be performed separately for each bottle, so first the steps has to be
performed for bottle 1, and then for 2 and finally for 3 bottle.)
12. Put the yeast in the tubes.
13. Now put the corks with the rubber hoses in it in the test tubes.
(the steps 14, 15 and 16 all has to done while the bottle is upside down in the water, otherwise
the test results will not be accurate).
14. Let it in the bath for 2 days.
15. After 2 days take the rubber hoses out of the bottles.
16. Replace the caps with the holes for caps without holes.
17. Weigh the bottles.
18. Clean the tubes bottles and the rubber hoses.
19. Repeat step 1-18 another 2 times, so a total of 3 times.
#1.
1 with Dr. Oetker and 2 with Fleischmann’s.*
#2.
2 with Dr. Oetker and 1 with Fleischmann’s.
#3.
1 with Dr. Oetker and 2 with Fleischmann’s.
20. The final and last step is to put all the materials used for the experiment in the right places.
*The first time we did the test, we tried to do it with 0,4g yeast and 50ml D-glucose solution. But the
tubes were filled too full and thus were therefore gone over. We tried this because we should have
had better results when it had succeeded. After this time we decided to do the tests with 0,4g yeast
and 25ml D-glucose.
Further comments:
At first we wanted to test 3 sorts of yeast but we decided to test 2 sorts, because we had only 6
measurements left, after the first time when the test failed. The reason was that there was a chance
of failing again and when that would happen we wouldn’t have any results. We should have only 2
results of each type and when was a big difference between the two measurements we wouldn’t
know which to thrust. In the end this was a smart decision because there were 2 other
measurements that failed (1x bakers-yeast and 1x super-yeast).
Table 1. The amount of CO2 in the bottle
H2O (in g) H2O (in g/L)
1
0,998
2
0,998
3
0,998
4
0,998
5
0,998
* = H2O(g) / ρ (H2O)
** = CO2(l) * ρ (0,001986)
*** = H2O(g) - CO2(g)
H2O (in l)*
1,002
2,004
3,006
4,008
5,010
CO2 (in l)
1,002
2,004
3,006
4,008
5,010
CO2 (in g/L)
0,001986
0,001986
0,001986
0,001986
0,001986
CO2 (in g)**
0,001990
0,003980
0,005970
0,007960
0,009950
Mass loss (in g)***
0,99801002
1,99602004
2,99403006
3,99204008
4,9900501
0,012000
y = 0,001994x
0,010000
0,008000
0,006000
0,004000
0,002000
0,000000
0
1
2
3
4
5
6
Figure 2. The mass loss plotted against the CO2(g)
We used random masses for the water loss and from there we calculated what the other values have
been. And with this figure we made a function for the mass loss in the bottle. We are measuring the
mass loss and if we want to know how much CO2 (g) there was produced by the yeast the only thing
we have tot do is to fill the measurement as the “x” in the formula of figure 2. So if we multiply the
rectifiers coefficient with the measured mass loss we know how much CO2 has arisen in the bottle.
And with this information we can say which type of yeast is the best.
Results:
Mass of the bottle
before the
experiment (in g)
Mass of the bottle
after
the experiment (in g)
Mass
difference
(in g)*
CO2
(in g)**
Molar
(M)
Amount
millimoles***
523,37
521,65
389,03
391,88
134,34
129,77
0,2679
0,2588
44,01
44,01
6,09
5,88
384,91
390,84
134,24
132,17
0,2677
0,2635
44,01
44,01
6,08
5,99
Dr. Oetker
Fleischmann's
519,15
523,01
* = mass before - mass after
** = mass difference * 0,001994
*** = CO2 (g) / Molar
Conclusion:
The results are unfortunately not very clear. If we should go for the highest average. We have to say
that Fleischmann’s yeast is better, but the difference is not very big. The average of the
measurements of Dr. Oetker’s yeast is 5,98 millimoles and the yeast of Fleischmann’s has a average
of 6,04 millimoles. This is of course very disappointing. But besides the fact that we have only 2
measurements per type yeast is even more disappointing. Because of this we can’t say exactly which
type of yeast is better. But the fact that the results of these two types of yeast is so close to each
other notes that even if we can rely on the averages and therefore may say Fleischmann’s is better
(and that would mean our hypotheses was right), but we can not say he is better because the
difference was so small that any difference is only noticeable with the right equipment.
The conclusion is we can draw no conclusion from these data and that when we want to say that one
is better in the fermentation process than the other there is certainly further research needed.
Evaluation:
As we said in the conclusion, the only way to draw a good conclusion is to get better results en also
more. We only had two measurements per type and that is far too little. If we also got the chance we
should do the test with higher amounts. So more yeast and D-glucose solution. This way the
difference between the yeast types would become clearer. Also the errors in the error discussion
below must have been solved.
Error discussion:
Because the rubber bands exert a certain pressure, the bottles can be dented by that
pressure so that the bottles lose an amount of water. This changes the mass of the bottle. This makes
the test results clearly less accurate.
In the cups there could be some yeast that stick to the cup. So not all the yeast could be
involved in the test. This also makes the test less accurate.
Too little good measurements. Because of this we couldn’t draw a real conclusion.
Bibliography:
 Binas havo/vwo, Wolters-Noordhoff, 5th edition