Final experiment by Chan Wing Sze Kelly (3035698222)
Final experiment: How do different acids used affect the stability of the emulsion formed in vinaigrette
Reflections after the first experiment:
After the first experiment, I did some research and I made some improvements to further prove my hypothesis of "Different acids used will affect the stability of the emulsion formed due to the difference in pH value of the acid."According to Juttulapa (2013), she claims that pH affects the stability of the emulsion, which affects the viscosity of the emulsion. The lower the pH of the acid, the more stable and viscous the emulsion formed is. Therefore, I decided to amend my first experiment by using the solutions I suggested in the previous post and see if I can come up with another experiment to prove my hypothesis.
The following is what I will be experimenting in this post:
1. Experiment 1: Testing the ratio of (change in the height of acid to the emulsion layer) to investigate and compare the stability of the emulsion formed by using different acids with different pH values.
2. Experiment 2: Testing the viscosity of the emulsion by measuring the time needed for the marble to sink to the bottom of the jar.
Results which I expect:
In experiment 1, I expect the emulsion using lemon juice will have the lowest ratio after 5 minutes, as lemon juice has the lowest pH.In experiment 2, I expect the marble will sink to the bottom the fastest emulsion in the malt vinegar emulsion, as the emulsion formed should be the least viscous.
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Experiment 1:
Changes that I have made:
1. I used a smaller and narrower glass jar instead of a plastic container so that the results are more observable.
2. I used 2 different measuring spoons, which a red smaller measuring spoon (5ml) is used to measure the acid, while a blue larger measuring spoon (15ml) instead of just using a large measuring jug to increase the precision.
3. The amount of ingredients used, I used 60ml of oil and 20ml of acid this time.
4. I used a sieve to remove all the lemon pulps and seeds so that I will only obtain the lemon juice.
5. I shook the mixture vigorously for 30 times for each, instead of shaking for one minute without counting.
6. I measured the change in height of the acid and emulsion layers at 30-second intervals.
Here is a video of my experiment, please enjoy:)
- 60 ml oil
- 20 ml acid (red wine vinegar, malt vinegar, lemon juice)
Utensils used:
- glass jar
Tools used:
- measuring spoons
- sieve
- knives
- timer (tablet)
Step 1: Measure an equal amount of acids (20ml) for each set-up with the same measuring spoon, and pour into the glass jar, rinse the cup with water after measuring each time to ensure no contamination.
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| Red wine vinegar (A) |
 |
| Malt vinegar (B) |
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| Lemon juice (C) |
Step 2: Measure the height of each of the acids.
Step 3: Measure an equal amount of oil (60ml) for each set-up with the same measuring spoon.
Step 4: Directly pour the oil into the 3 set-ups respectively.
Ingredients used for each set-up: (from experiment 1)
- 15 ml from each set-up from experiment 1
Utensils used:
- glass jar
- test tubes
- test tube rack
- marble
Tools used:
- measuring spoons
- timer (tablet)
Step 1: Shake the glass jar for 50 times to ensure the emulsion can be temporarily formed.
Step 2: Measure an equal amount of acids (15ml) from each set-up respectively with the 15ml blue measuring spoon, and pour it into the test tube.
Step 3: Drop the marble into the test tube and measure the time needed for the marble to drop to the bottom of the test tube. Record the time needed for each set-up.
Step 4: Repeat step 1 to 3 for two more times.
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Results:
The experiment was a failure as my marble was too big, it got stuck in the middle of the test tube. Therefore, I did not continue to conduct the experiment.
However, as I had a new observation in the first experiment, which the density and size of the oil droplets in the emulsion layer is the largest in the malt vinegar-oil emulsion; while, which the density and size of the oil droplets in the emulsion layer is the smallest in the lemon juice-oil emulsion.
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Step 4: Directly pour the oil into the 3 set-ups respectively.
Step 5: Measure the height of the oil layer.
Step 6: Calculate the ratio of (the height of the oil layer : the height of the acid layer).
A (red wine vinegar)
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B (malt)
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C (lemon juice)
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Original height of oil layer
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2.2 cm
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2.0 cm
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2.1 cm
|
Original height of acid layer
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1.1 cm
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1.0 cm
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0.9 cm
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Original ratio of
(height of oil layer: height of acid layer)
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2 : 1
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2 : 1
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2.33 : 1
|
Step 7: Shake each set-up vigorously for 30 times.
Step 8: Stop shaking and let the mixture sit.
Step 9: Observe and measure the change in the height of the emulsion layer and the height oil layer at 1-minute intervals, record down the heights with a ruler.
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Results of experiment 1:
Set-up
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A (red wine vinegar)
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B (malt)
|
C (lemon juice)
|
height of acid layer after sitting for 30 sec
|
0 cm
|
0 cm
|
0cm
|
height of emulsion layer after sitting for 30 sec
|
3.3 cm
|
3.0 cm
|
3.0 cm
|
height of acid layer after sitting for 1 min
|
0 cm
|
0 cm
|
0 cm
|
height of emulsion layer after sitting for 1 min
|
3.3 cm
|
3.0 cm
|
3.0 cm
|
height of acid layer after sitting for 1 min 30 sec
|
0.1 cm
|
0 cm
|
0 cm
|
height of emulsion layer after sitting for 1 min 30 sec
|
3.2 cm
|
3.0 cm
|
3.0 cm
|
height of acid layer after sitting for 2 mins
|
0.2 cm
|
0.1 cm
|
0 cm
|
height of emulsion layer after sitting for 2 mins
|
3.1 cm
|
2.9 cm
|
3.0 cm
|
height of acid layer after sitting for 2 mins 30 sec
|
0.3 cm
|
0.3 cm
|
0.05 cm
|
height of emulsion layer after sitting for 2 mins 30 sec
|
3.0 cm
|
2.7 cm
|
2.95 cm
|
height of acid layer after sitting for 3 mins
|
0.4 cm
|
0.4 cm
|
0.05 cm
|
height of emulsion layer after sitting for 3 min
|
2.9 cm
|
2.6 cm
|
2.95 cm
|
height of acid layer after sitting for 3 mins 30 sec
|
0.45 cm
|
0.5 cm
|
0.05 cm
|
height of emulsion layer after sitting for 3 mins 30 sec
|
2.85 cm
|
2.5 cm
|
2.95 cm
|
height of acid layer after sitting for 4 mins
|
0.5 cm
|
0.5 cm
|
0.05 cm
|
height of emulsion layer after sitting for 4 mins
|
2.8 cm
|
2.5 cm
|
2.95 cm
|
height of acid layer after sitting for 4 mins 30 sec
|
0.5 cm
|
0.6 cm
|
0.05 cm
|
height of emulsion layer after sitting for 4 mins 30 sec
|
2.8 cm
|
2.4 cm
|
2.95 cm
|
height of acid layer after sitting for 5 mins
|
0.5 cm
|
0.7 cm
|
0.1 cm
|
height of emulsion layer after sitting for 5 mins
|
2.8 cm
|
2.3 cm
|
2.9 cm
|
Set-up
|
A (red wine vinegar)
|
B (malt)
|
C (lemon juice)
|
ratio of
(height of acid layer : emulsion layer:) after 30 sec
|
0
|
0
|
0
|
ratio of
(height of acid layer : emulsion layer:) after 1 min
|
0
|
0
|
0
|
ratio of
(height of acid layer : emulsion layer:) after 1 min 30 sec
|
0.0313
|
0
|
0
|
ratio of
(height of acid layer : emulsion layer:) after 2 mins
|
0.0645
|
0.0345
|
0
|
ratio of
(height of acid layer : emulsion layer:) after 2 mins 30 sec
|
0.100
|
0.111
|
0
|
ratio of
(height of acid layer : emulsion layer:) after 3 mins
|
0.138
|
0.154
|
0.0169
|
ratio of
(height of acid layer : emulsion layer:) after 3 mins 30 sec
|
0.158
|
0.200
|
0.0169
|
ratio of
(height of acid layer : emulsion layer:) after 4 mins
|
0.179
|
0.200
|
0.0169
|
ratio of
(height of acid layer : emulsion layer:) after 4 mins 30 sec
|
0.179
|
0.250
|
0.0169
|
ratio of
(height of acid layer : emulsion layer:) after 5 mins
|
0.179
|
0.304
|
0.0345
|
Conclusion: Malt has the highest "acid to emulsion layer" ratio, which indicates that it forms the least stable emulsion with oil. While lemon juice has the smallest "acid to emulsion layer" ratio, which indicates that it forms the most stable emulsion with oil.
From Experiment 1, it quantitative proved my hypothesis that "Using different acids affect the stability of the emulsion formed, due to the difference in pH." and that "The lower the pH value, the more stable the emulsion."
Additional Observation and finding:
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| Comparing A with B, the acid droplets in B are much more larger and observable in the emulsion layer. |
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| The acid droplets dispersed in the emulsion layer is the largest and most observable in B,. In A, some small acid droplets can be observed; but in C, hardly any acid droplets can be observed, but there is a thin darker yellow layer on the top of the mixture that can be seen. |
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Experiment 2: Measuring the viscosity of the emulsions by measuring the time needed for the marble to sink to the bottom of the test tube
Ingredients used for each set-up: (from experiment 1)
- 15 ml from each set-up from experiment 1
Utensils used:
- glass jar
- test tubes
- test tube rack
- marble
Tools used:
- measuring spoons
- timer (tablet)
Step 1: Shake the glass jar for 50 times to ensure the emulsion can be temporarily formed.
Step 2: Measure an equal amount of acids (15ml) from each set-up respectively with the 15ml blue measuring spoon, and pour it into the test tube.
Step 3: Drop the marble into the test tube and measure the time needed for the marble to drop to the bottom of the test tube. Record the time needed for each set-up.
Step 4: Repeat step 1 to 3 for two more times.
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Results:
The experiment was a failure as my marble was too big, it got stuck in the middle of the test tube. Therefore, I did not continue to conduct the experiment.
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