Quiz1. When we extract oil what must we do to the seeds first?

2. Once the oil is dissolved in a solvent what process happens next?

3. With lavender oil the process is much easier, how do we extract their oils?

4. What colour does bromine/iodine change to, to detect certain oils?

5. What does change the colour of bromine/iodine- saturated or unsaturated?

6. Vegetable oils are unsaturated but what happens to bromine if the product is saturated like lard?

Answers

1. Crush them

2. Distillation

3. Boil the lavender

4. Turns Clear

5. Unsaturated

6. Stays yellow

Cooking with Vegetable Oils

Saturated Unsaturated

• The temperature that liquid boils at depends on the forces between molecules.

• Bigger the force the higher the boiling point.

What do you notice about the boiling points?

Water- 100 C

Safflower - 510 F (266 C) Soybean - 495 F (257 C)

Corn - 475 F (246 C)

Peanut - 440 F (227 C)

Sesame - 420 F (216 C)

Olive - 375 F (191 C)

• Molecules in vegetable oils are bigger compared to water.

• This means forces between molecules in the vegetable oil is much larger.

• This increases its boiling point compared to water.

• Cooking with vegetable oils means the food cooks more quickly, changes colour and is crisper.

• Cooking with oil means the food will absorb the oil.

• Oils contain a lot of energy.

• So fried food contains more energy compared to boiled food.

• We can increase the boiling points of oils by adding hydrogen to molecules.

• Doing this increases the melting point and they become solid at room temperature.

• This is how margarines are made.

• This process is called hydrogenation or hardening.

Hydrogenation

• Vegetable oils are hardened by reacting them with hydrogen gas at about 60ºC.

• A nickel catalyst is used to speed up the reaction.

• The double bonds are converted to single bonds by the hydrogenation.

The boiling points of vegetable oils are

_________ than the boiling point of water. This

means that food cooked in oil _______ different to

boiled food. It also contains more _________. The

boiling and __________ points of oils may also be

raised by adding ________ to their molecules. We call this _______ the oil.

Energy Hardening Higher Hydrogen Melting Tastes

Extension

1. What is hydrogenation/hardening?

2. What two conditions are needed for this process?

• Make a leaflet for the public to explain what the differences are between cooking with water and vegetable oil.

- Think about the boiling points

- How they cook the food differently

- Why fried foods contain more calories

- How margarines are like oils and how they are made.