Properties Of Fats And Oils

Question 1

Aeration

Answer 1

When fats are beaten with sugar air becomes trapped.

This gives a spongy and light texture once the food is cooked.

Question 2

Shortening

Answer 2

Gives the flour a waterproof coating. This prevents long gluten molecules forming when water is added.
The dough cannot become stretchy.

Question 3

Plasticity

Answer 3

We are able to spread and manipulate them.
Fats contain a mixture of triglycerides which melt at different temperatures.
More unsaturated fats the more plasticity.
Plasticity is useful for decorating cakes, shortening, spreading.
Vegetable fats are easier to spread because the triglycerides have low melting points.

Question 4

Emulsification

Answer 4

Oily and watery liquids are shaken together. Oil and water don’t mix but emulsions separate out again.
The emulsifier molecules have two ends hydrophilic (attracted to water) and hydrophobic (repulsed by water). Hydrophilic bonds to water and hydrophobic bonds to oil. This holds oli and water together in a stable emulsion.

Question 5

Emulsions in sauces and salad dressings.

Answer 5

Hollandaise sauces = butter, water, lecithin, lemon juice

1. Melt butter
2. Mix egg yolk an lemon juice
3. Gently warm the mixture over a pan of simmering water.
4. Slowly add the melted butter constantly whisking.
5. Keep whisking until mixed together and is smooth.