Extracting Vegetable Oils

L.O: To understand where different oils come from and which

are saturated and unsaturated

Starter: Make a list of as many different oils as you can (Hint: think about cooking)

Extracting Oil

Step 1: Crush the plant

Step 2: Remove oil by pressing

OR step 3: Remove oil by distillation

Extracting by crushing

1. Copy the table and complete it as do the activity.

2. Crush each of the foods with a pestle and mortar.

3. Test for fats (oil) using the filter paper – it will look clear when held up to the light if the food contains oil.

4. Make a note of how much oil you think you extracted.

Food Contains oil?

or

How much oil

What would you have to do with the crushed food next to get pure oil?

Distillation

The oil and water have a lower boiling point, so evaporate before the other impurities do. An emulsion of water and oil is distilled.

This means that the oil will be separated.

Distillation Questions

1. What is the difference between the solution in the side armed flask and the solution in the conical flask?

2. Why do the liquids get separated?

3. What impurities get removed in this way?

How Healthy Are Oils?• Vegetable oils contain a lot of energy – over

double the energy that is in sugar.• Oils may also contain other useful nutrients e.g.

vitamin e in vegetable oils, and omega 3 in fish oils

But some oils are healthier than others and do not clog up your arteries.

Healthy and Unhealthy OilsUnhealthy oils:

Healthy oils:

“Saturated”

“Unsaturated”

Saturated vs. Unsaturated FatsSome oils are more healthy than others. These oils are “unsaturated” like ethene:

C CHH

HH

Ethene

Testing for double bonds:

Clearly, it is important for scientists to be able to test if a food contains “healthy” unsaturated fats or “unhealthy” saturated fats. Here’s how it’s done:

Oil (in ethanol)Bromine goes colourless

Bromine water

Saturated vs. Unsaturated FatsIodine also tests for unsturated oils C C

HH

HH

Ethene

Testing for double bonds:

The reddy brown colour of iodine turns colourless

OilIodine goes colourless

Iodine

Copy and fill in this table

Oil Colour after Bromine Test

Colour after iodine test

Saturated or Unsaturated

Does it contain double bonds?

1

2

3

4

5

6

Is there a pattern linking the state of the fat or oil at room temperature and its chemical nature (saturated or unsaturated)?

Summary: Fill in the gaps

We can extract vegetable oils from some plants by _______ or ________. Vegetable oils are particularly important as foods because they contain a lot of _______. Some vegetable oils contain carbon – carbon double bonds – we call these ________ vegetable oils. They can be detected by reacting them with _______ or ________.

Bromine distillation energy

iodine pressing unsaturated