Why does foam form on orange squash?

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In summary: Substances with a lower surface tension (like squash) will form bubbles while those with a higher surface tension (like water) will not.
  • #1
wildwildebees
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Why do I get a foam forming on my glass of squash, but not just a glass of water?

i.e.

If I fill a glass with water from the tap, with the water flowing pretty fast, there are only a very few, quite large, bubbles which form on the surface of the water, and they quickly dissipate away.

If I add a small amount of squash (cordial) to the bottom of the glass and then add the water in the same way, a large number of small bubbles (a foam, I suppose) forms on the surface, and takes 3 or 4 seconds to disappear.

Anyone know what's responsible for the difference? It seems related to a soap foam, but I wouldn't have thought there any any ingredients in common...

Cheers!
 
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  • #2
Hmm. Could it have something to do with the viscosity of the substance compared to water?
 
  • #3
And/or
One agent needed to produce foam is a surficant which lowers the surface tension of water. Some ingrediant in the sqaush could midly be providing this feature, So in essence the action is the same as a soap. You could search for more information about foam, suficants, foaming agents.
 
  • #4
Yes surfactants - presumably these don't actually create bubbles but just allow any air bubbles which enter the liquid to be contained? Since the surface tension is lower, so the restoring force which acts to close the bubble to reduce surface area is lower.

I've had a look around to see what the surfactants could be and couldn't find much - citric acid is present in 3 different liquids I tested, but then I also tried pure lemon juice and that didn't bubble at all! Also, milk does create bubbles. Very confusing. But I suppose this is really getting into chemistry now.
 
  • #5
Not surfactants in fact quite the opposite - oils.

the cordial contains oils (in fact that's what gives the flavouring and smell of orange)

The oil is hydrophobic and so stabilise the bubble.

Regards

Sam
 
  • #6
sambristol said:
Not surfactants in fact quite the opposite - oils.

the cordial contains oils (in fact that's what gives the flavouring and smell of orange)

The oil is hydrophobic and so stabilise the bubble.

Regards

Sam

I was under the impression that light oils, having a different surface tension than water, de-stabilise foaming.
 

1. Why does foam form on orange squash?

Foam on orange squash is formed due to the presence of surfactants, which are chemical compounds that reduce the surface tension of water. Orange squash contains surfactants that help to mix the syrup and water, creating tiny air bubbles that result in foam formation.

2. Is foam on orange squash harmful to consume?

No, foam on orange squash is not harmful to consume. It is a natural result of the ingredients in the squash and does not pose any health risks. However, if you have concerns, you can always skim off the foam before drinking.

3. Can I prevent foam from forming on my orange squash?

Yes, you can prevent foam from forming on your orange squash by adding a few drops of vegetable oil to the mixture. This will help to break down the surfactants and reduce foam formation. Alternatively, you can also mix the squash and water slowly, allowing the foam to dissipate before adding more liquid.

4. Why does foam on orange squash disappear over time?

Foam on orange squash disappears over time because the gas bubbles in the foam eventually burst and release the air. This is due to the instability of the foam structure, which cannot hold the bubbles for an extended period. The foam may also disappear due to evaporation of the water in the solution.

5. Can I use a different type of container to prevent foam on my orange squash?

Yes, using a different type of container can help to prevent foam on your orange squash. For example, using a wide, shallow container instead of a tall, narrow one can reduce the amount of agitation and result in less foam formation. Additionally, using a container with a lid can also help to prevent foam by trapping the gas bubbles and preventing them from escaping.

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