Emulsions Flashcards
Give three common examples of where you might find emulsions
- Food
- Cosmetics
- Paint
Which 2 substances can emulsions be made from?
Water and oil
What, broadly speaking, are emulsions made up of?
Lots of DROPLETS of one liquid SUSPENDED in another liquid.
Give 2 examples of emulsions using oil and water
A…
1. Oil-in-water emulsion (oil droplets suspended in water)
or a…
2. Water-in-oil emulsion (water droplets suspended in oil)
Complete the sentence:
Emulsions are _______ than either oil or water.
Emulsions are THICKER than either oil or water.
Give an example of an everyday emulsion and what it is made of
Mayonnaise
SUNFLOWER (or olive) oil, and VINEGAR
What do the physical properties of emulsions make them suited for? Example?
Lots of uses in foods e.g. as salad dressings and sauces
How is a salad dressing made?
By shaking olive oil and vinegar together forming an EMULSION that COATS salad better than PLAIN oil or PLAIN vinegar
Generally, how does having more oil in an oil-in-water emulsion affect its density?
The MORE oil, the THICKER the emulsion
Give an example of an oil-in-water emulsion with not much oil and a lot of water, and the percentages of oil
Milk / cream
Full-fat: 3%
Single cream: 18%
Double cream: 50% - (technically doesn’t have a lot more water than oil but nm)
What extra ingredient (besides oil and water), do the oil-in-water emulsions WHIPPED CREAM and ICE CREAM both contain?
Air
Why does WHIPPED CREAM contain air?
To give it a FLUFFY, frothy consistency for use as TOPPING
Why does ICE CREAM contain air?
To give it a SOFTER TEXTURE, which makes it easier to SCOOP out of a tub
What kind of COSMETIC is usually an oil-in-water emulsions?
Moisturising lotion (moisturiser)
Why are most MOISTURISERS emulsions?
Because the SMOOTH texture of an emulsion makes it easy to RUB into the skin
Basically, what do emulsifiers do?
Help OIL and WATER mix
Why do some foods contain emulsifiers?
To help oil and water mix
Complete the sentence:
Oil and water mixtures naturally ______ ___ .
Oil and water mixtures naturally SEPARATE OUT .
Complete the sentence:
Emulsifiers are molecules with one part that’s attracted to ______ and another part that’s attracted to _____ or ____ .
Emulsifiers are molecules with one part that’s attracted to WATER and another part that’s attracted to OIL or FAT .
What is the bit of an emulsifier that’s attracted to WATER called?
Hydrophilic
What is the bit of an emulsifier that’s attracted to OIL called?
Hydrophobic
What do the HYDROPHILIC ends of each emulsifier molecule latch onto?
Water MOLECULES
What do the HYDROPHOBIC ends of each emulsifier molecule latch onto?
Oil MOLECULES
State the 3 points explaining what happens when you shake oil and water together with an emulsifier
- The oil forms droplets, SURROUNDED by a coating of EMULSIFIER, with the HYDROPHILIC end facing OUTWARDS.
- Other oil droplets are REPELLED by the HYDROPHILIC bit of the emulsifier, while water molecules LATCH onto it.
- This stops the emulsion separating out.
What are the 2 pros of using emulsifiers?
- They STOP emulsions from SEPARATING out, giving them a longer SHELF LIFE
- They allow food companies to produce food that’s lower in FAT but still has a GOOD TEXTURE
What is the downside of using emulsifiers? (give specific example)
Some people are ALLERGIC to certain emulsifiers.
E.g. EGG YOLKS
In an emulsion what does NOT happen to a liquid in another liquid?
One liquid is not DISSOLVED in another liquid - it is SUSPENDED!!!
