Repost of the First Experiment by Chan Wing Sze Kelly (3035698222)

Repost of the first Experiment: How do different acids used affect the stability of the emulsion formed in vinaigrette

Equipments to prepare before cooking:
- plastic container
- measuring cup
- ruler
- timer (phone)

Ingredients to prepare:
- oil
- different kinds of acid (I chose to use lemon juice, red wine vinegar, and malt vinegar)

Who? 

Chan Wing Sze Kelly

What is my hypothesis?

Different acids used will affect the stability of emulsion formed due to the difference in pH value.  

acid	A (red wine vinegar)	B (malt)	C (lemon juice)
pH value	2.6 – 2.8	3.5	2.0

Where?

In my kitchen.

When?

To carry out the tests after preparing three vinaigrettes with different acids.

Why is the experiment important?

As there are different recipes using different acids as their vinaigrette base. Therefore, I would like to investigate whether using different acids will have different effects on the stability of the emulsion formation.

How can I prove my hypothesis?

By measuring the time taken for the shaken mixture to separate into 2 layers after it is left alone. The longest time taken indicates the best emulsion formed.

Changes that I have made:

In the original first experiment that I have posted, my question was simply "how the acid used affects the formation of the vinaigrette, however, after conducting reconsidering my experiment, I decided to change it to "how the acid used affects the stability of the emulsion formed", as I think this explains the aim of my experiment more precisely.

Also, in the original recipe that I have posted, seasonings and the emulsifier (mustard) were included, however, I tried to make the original recipe once, and it took me 2 weeks before I was able to see observable results. (Picture below) It was a huge failure, and I decided to do the first experiment again and repost it, as I did not want to waste ingredients and I would like to consider carefully before I conduct the experiment.

My failed attempt by following the recipe I posted to investigate the effect of acids on the emulsion formed as it took over days to observe changes due to the presence of the mustard (emulsifier)

After careful considerations, I have decided to use ONLY OIL AND ACID. As this would allow me to observe any changes most quickly and effectively without any disturbance caused by other ingredients. Also, as I figured out that the liquid weight is different from the liquid volume, therefore I did not use "grams" for my ingredients and used "milliliters" by using a measuring cup instead to ensure I have the 3:1 of oil to acid ratio.

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Amount of Ingredients used for EACH set-up:

- 90 ml of oil

- 30 ml of acids (lemon juice, malt vinegar, red wine vinegar)

 

Set-up A: Malt vinegar                       Set-up B: Red wine vinegar                      Set-up C: lemon juice

Step 1: Measure an equal amount of acids (30ml) for each set-up with the same measuring cup, rinse the cup with water after measuring each time to ensure no contamination. 

Step 2: Transfer the acids into the 3 plastic containers respectively.

Step 3: Measure the height of each of the acids.

Step 4: Measure an equal amount of oil (90ml) for each set-up with the same measuring cup.

Step 5: Directly pour the oil into the 3 set-ups respectively. 

Step 6: Measure the height of the oil layer.

Step 7: Calculate the ratio of (the height of the oil layer : the height of the acid layer).

Set-up	A (red wine vinegar)	B (malt)	C (lemon juice)
Original height of oil layer	2.7cm	2.8cm	2.6cm
Original height of acid layer	1.1cm	1.1cm	1.3cm
Original ratio of (height of oil layer: height of acid layer)	2.45	2.54	2

Step 8: Shake each set-up for 1 minute.

A after shaking for one minute

     

B after shaking for one minute

C after shaking for one minute

Step 9: Stop shaking and let the mixture sit.

Step 10: 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

A (red wine vinegar) after sitting for:

for 1 minute

for 2 minutes

for 3 minutes

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B (malt vinegar) after sitting for:

for 1 minute

for 2 minutes

for 3 minutes

____________________________________________________________________

C (lemon juice) after sitting for:

for 1 minute

for 2 minutes

for 3 minutes

   

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Summary of the above results

Set-up	A (red wine vinegar)	B (malt)	C (lemon juice)
height of oil layer after sitting for 1 min	0cm	0.8cm	0cm
height of emulsion layer after sitting for 1 min	3.8cm	3.1cm	3.9cm
height of oil layer after sitting for 2 min	0.1cm	0.8cm	0cm
height of emulsion layer after sitting for 2 min	3.7cm	3.1cm	3.9cm
height of oil layer after sitting for 3 min	0.2cm	0.8cm	0cm
height of emulsion layer after sitting for 3 min	3.6cm	3.1cm	3.9cm

Set-up	A (red wine vinegar)	B (malt)	C (lemon juice)
ratio of  (height of oil layer : emulsion layer) after 1 min	0	0.258	0
ratio of  (height of oil layer : emulsion layer) after 2 mins	0.0270	0.258	0
ratio of  (height of oil layer : emulsion layer) after 3 mins	0.0556	0.258	0

           

Conclusion of the above results:

acid	A (red wine vinegar)	B (malt)	C (lemon juice)
pH value	2.6 – 2.8	3.5	2.0

Lemon juice forms the most stable emulsion with oil, while malt vinegar forms the least stable emulsion with oil.

From this, it is proved that the use of different acids indeed affects the stability of the formation of the emulsion in the vinaigrette mixture.  And the lower the pH value (the more acidic), the more stable is the emulsion formed.

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Possible source of errors:

Problem 1:The exact height of the different layers are difficult to measure, using bare eyes cannot detect small changes. 

Solution: I will try using a smaller and narrower container so that the changes in height will be more significant.

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Problem 2: Using a measuring jug is very inaccurate, the 3:1 volume ratio of oil : acid is not precise.

Solution 2: I will try using a measuring spoon instead to try to increase the accuracy.

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Problem 3: One-minute interval is not accurate enough.

Solution 3: I will try to record 30-seconds intervals next time.

Posted by Chan Wing Sze Kelly (3035698222)