Emulsions

Question 1

Give three common examples of where you might find emulsions

Answer 1

1. Food
2. Cosmetics
3. Paint

Question 2

Which 2 substances can emulsions be made from?

Answer 2

Water and oil

Question 3

What, broadly speaking, are emulsions made up of?

Answer 3

Lots of DROPLETS of one liquid SUSPENDED in another liquid.

Question 4

Give 2 examples of emulsions using oil and water

Answer 4

A…
1. Oil-in-water emulsion (oil droplets suspended in water)

or a…
2. Water-in-oil emulsion (water droplets suspended in oil)

Question 5

Complete the sentence:

Emulsions are _______ than either oil or water.

Answer 5

Emulsions are THICKER than either oil or water.

Question 6

Give an example of an everyday emulsion and what it is made of

Answer 6

Mayonnaise

SUNFLOWER (or olive) oil, and VINEGAR

Question 7

What do the physical properties of emulsions make them suited for? Example?

Answer 7

Lots of uses in foods e.g. as salad dressings and sauces

Question 8

How is a salad dressing made?

Answer 8

By shaking olive oil and vinegar together forming an EMULSION that COATS salad better than PLAIN oil or PLAIN vinegar

Question 9

Generally, how does having more oil in an oil-in-water emulsion affect its density?

Answer 9

The MORE oil, the THICKER the emulsion

Question 10

Give an example of an oil-in-water emulsion with not much oil and a lot of water, and the percentages of oil

Answer 10

Milk / cream

Full-fat: 3%
Single cream: 18%
Double cream: 50% - (technically doesn’t have a lot more water than oil but nm)

Question 11

What extra ingredient (besides oil and water), do the oil-in-water emulsions WHIPPED CREAM and ICE CREAM both contain?

Answer 11

Air

Question 12

Why does WHIPPED CREAM contain air?

Answer 12

To give it a FLUFFY, frothy consistency for use as TOPPING

Question 13

Why does ICE CREAM contain air?

Answer 13

To give it a SOFTER TEXTURE, which makes it easier to SCOOP out of a tub

Question 14

What kind of COSMETIC is usually an oil-in-water emulsions?

Answer 14

Moisturising lotion (moisturiser)

Question 15

Why are most MOISTURISERS emulsions?

Answer 15

Because the SMOOTH texture of an emulsion makes it easy to RUB into the skin

Question 16

Basically, what do emulsifiers do?

Answer 16

Help OIL and WATER mix

Question 17

Why do some foods contain emulsifiers?

Answer 17

To help oil and water mix

Question 18

Complete the sentence:

Oil and water mixtures naturally ______ ___ .

Answer 18

Oil and water mixtures naturally SEPARATE OUT .

Question 19

Complete the sentence:

Emulsifiers are molecules with one part that’s attracted to ______ and another part that’s attracted to _____ or ____ .

Answer 19

Emulsifiers are molecules with one part that’s attracted to WATER and another part that’s attracted to OIL or FAT .

Question 20

What is the bit of an emulsifier that’s attracted to WATER called?

Answer 20

Hydrophilic

Question 21

What is the bit of an emulsifier that’s attracted to OIL called?

Answer 21

Hydrophobic

Question 22

What do the HYDROPHILIC ends of each emulsifier molecule latch onto?

Answer 22

Water MOLECULES

Question 23

What do the HYDROPHOBIC ends of each emulsifier molecule latch onto?

Answer 23

Oil MOLECULES

Question 24

State the 3 points explaining what happens when you shake oil and water together with an emulsifier

Answer 24

1. The oil forms droplets, SURROUNDED by a coating of EMULSIFIER, with the HYDROPHILIC end facing OUTWARDS.
2. Other oil droplets are REPELLED by the HYDROPHILIC bit of the emulsifier, while water molecules LATCH onto it.
3. This stops the emulsion separating out.

Question 25

What are the 2 pros of using emulsifiers?

Answer 25

1. They STOP emulsions from SEPARATING out, giving them a longer SHELF LIFE
2. They allow food companies to produce food that’s lower in FAT but still has a GOOD TEXTURE

Question 26

What is the downside of using emulsifiers? (give specific example)

Answer 26

Some people are ALLERGIC to certain emulsifiers.

E.g. EGG YOLKS

Question 27

In an emulsion what does NOT happen to a liquid in another liquid?

Answer 27

One liquid is not DISSOLVED in another liquid - it is SUSPENDED!!!