Emulsion
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An emulsion is a mixture of two liquids that would not normally mix, such as oil and vinegar. Emulsifiers help form emulsions by lowering the oil-water interfacial tension, allowing the liquids to combine. Emulsifiers create a film around globules of one phase that repel each other and prevent the emulsion from separating. Stabilizers also help emulsions resist change over time by increasing viscosity and decreasing droplet movement.
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Emulsion
- 1. By : Abirami Nadarajan Photo courtesy by Ivan Danielewicz CC (BY-NC-SA
- 2. Is a mixture of two liquids that would ordinarily not mix together, like oil and vinegar.
- 3. Refers to the ability of an emulsion to resist change in its properties over time
- 8. Emulsifiers facilitate the formation of emulsion by lowering the oil-water interfacial tension. http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel_pre_2011/designerproduct s/foodanddrinkrev4.shtml Eg: PGA, Lecithin, Polysorbates.
- 9. The emulsifying agent creates a film over one phase that forms globules, which repel each other. This repulsive force causes them to remain suspended in the dispersion http://www.inkline.gr/inkjet/newtech/tech/dispersion/#electrostatic
- 10. Stabilizers : Increases the viscosity of the medium, which decreases the velocity at which droplet moves http://www.inkline.gr/inkjet/newtech/tech/dispersion/#electrostatic
Editor's Notes
- Part one: Emulsion Stability. Hello peoples, today we’re gonna talk about emulsion stability. But right before we start, I think we have to understand what is emulsion & emulsion stability.
- Emulsion is a mixture of 2 liquids that would ordinarily not mix together, like oil and vinegar. Try shaking oil and water, within minutes they’ll separate. Basically, the mixture of oil & water are thermodynamically unstable system, and they tend to dislike each other. How do we make em” like each other? We’ll get to there as the presentation moves on.
- As we’re looking for stable emulsion, it’s important to understand the “tiny-bit” of science behind it. Emulsion stability refers to the ability of an emulsion to resist change in its properties over time. Simply, how long the “oil & water” molecules stay and love each other. Theoretically, even stable emulsion will separate. After all, it’s a matter of time. And there’re few ways they can separate.
- To find out the ways they separate, we’ll look into mechanisms of emulsion instability.
- There are four types instability in emulsions: Flocculation occurs when there is an attractive force between the droplets, so they form flocs, like bunches of grapes. Coalescence occurs when droplets bump into each other and combine to form a larger droplet, so the average droplet size increasesover time. This involves breaking of interfacial film.Creaming occurs when droplets move upward due to gravity as they have lower density than the surrounding liquidSedimentation occurs when droplets move downwards due to their high density than surrounding liquids.
- Before we explain how to stabilize emulsion and avoid those emulsion instabilities, here a demo made by us. It’s not that good, but what we are trying to do is just to simply prove how an emulsifier and stabilizer could result in a stable emulsion.
- Now, we know that PGA + Starch results in stable emulsion, based on the demo. But how do they work? Lets go to the interesting theories.
- PGA functions as emulsifier. They facilitate the formation of emulsion by lowering the interfacial tension. The urge for the dispersed molecules to get back to each other has lessen to some extend, and they’ll stay away from each other pretty long time.
- Another theory would be the repulsion theory! The emulsifiers forms an electric charge cloud, causing the dispersed molecules to repel each other. As we’ll know, + does not like +, so they’ll stay away from each other!
- Lastly…pheew! We added in starch in the experiment! And the emulsion with both starch and pga was the most stable once. We know how PGA works, but how does starch increases the stability of emulsion? Well, starch is a stabilizer. It increases the viscosity of medium, which decreases at which droplet moves. Thus, our conclusion is the combination of stabilizer and emulsifier will give you a stable emulsion! And this is what you see in variety of food products! Thank you for watching, again, it mid not be the best, but we did our best. Bon Voyage!