To test for the presence of lipids in different food molecule
HOW DOES IT WORK?
Time allocation: 45 Min
Lipids dissolve in ethanol to form a clear solution. When water is added it forms a cloudy emulsion and this is why we use an ‘Emulsion Test’ to determine if a food group contains the presence of Fats and Oils. There are other types of tests such as the Grease Spot test which we will try in this experiment. This test is performed on Fats which are solids at room temperature.
Lipids are a very important component of living cells in plants and animals, cholesterol and triglycerides are lipids. In the human body they store energy as fat cells, work inside the cell to sent signals as well as form a structural component of the cell membranes.
- 2 x Test tubes
- 4 x Pipettes
- Test tube rack
- Ethanol 100ml
- 2x Filter paper circles
- Cooking oil
- Pestle and Mortar
- Label 2 test tubes A and B.
- Add 5ml of ethanol (or ether) to each of the two small test tubes A and B with a pipette.
- Add two to three drops of cooking oil in test tube A with another pipette.
- Shake thoroughly until the oil dissolves.
- Put a drop of the oil in ethanol solution on a piece of filter paper (or blotting paper) with a clean pipette. Mark the position of the drop and mark the filter paper with an A, for the corresponding Test tube. This is your control for the experiment.
- Using the pestle and mortar crush the peanuts thoroughly.
- Add the crushed peanuts to test tube B. Shake thoroughly until the samples and ethanol are mixed well.
- Put a drop of the peanuts in the ethanol solution on a piece of filter paper (or blotting paper) with a clean pipette. Mark the position of the drop and mark the filter paper with a B, for the corresponding test tube. This is your validation
- Leave the filter papers out to dry for a few minutes.
Note that in the experiment, a grease stain is left behind. In the control no such stain is created.
You can get a Negative or Positive result for this experiment:
Since only fats and oils leave behind a grease stain on filter paper, the test shows the substance contains fats and oils. It is concluded that the food substance contains Lipids as Lipids are also known as fats and oils
- This experiment requires adult wearing safety clothing and safety goggles.
- Always make sure that all chemicals are handled with care.
- Workstations must always be kept need and tidy.
- Be responsible when busy with experiments.
- Do not ingest the Ethanol as it is a processed form of Ethanol (Rectified or Denatured) it is not the same composition as the alcohol consumed for recreational purposes.