Protocol for Practical Classes

Subject: Lipids

Experiment 9 – characterization

Materials:

Provided by the students:

egg (1 for each group);

cooking oil (1 mL for each group)

Paper filter.

From the laboratory

3 bequers;

1 petri plate;

1 funnel;

Warm-bath;

Concentrated acetic acid - 5 mol/L (at teacher's table);

1 assay tube with 12 mL of acetone

1 assay tube with 3mL of KOH alcooholic– Tube B;

1 empty assay tube - Tube C

Metods:

Lipids extraction:

Oppen the egg separating its content in two bequers (albumen in one -1, egg yolk in another one -2) without breaching the membrane that involves the egg yolk;

Tranfer around 10 ml of the yolk to another bequer- 3(avoid using a pippete);

To this bequer, add 8ml of acetone:

Mix them untill the material aglutinates;

Wash the bequer 2;

Use the paper filter to filter the solution in the bequer 3 into the bequer 2;

Use more 4ml of acetone to help;

Tranfer all the material filtered to phe Petri plate;

Put it on the warm bath untill the total evaporation of the acetone;

Write down the observed results at each step.

Saponification:

Pour the content of the Tube B into the Petri plate;

Using the funnel, pour it all back into the Tube B. Add 1ml of cooking oil if there is little amount of lipids extract (lipids in the Petri plate).

Warm the Tube to 90^oC for 30 minutes;

Write down the observed results.

Analisys of soup characteristics:

Add 2mL of water to the Tube B;

Tranfer 3ml of the Tube B solution to the Tube C;

Agitate the Tube B;

Write down the observed results;

Add 2ml of the concentrated acetic acid to the Tube C, drop by drop;

Write down the observed results.

Objectives:

To understand the properties of the triacylglicerols and how they influence the solubilization.

To analyse the composition of these lipids using the observed results of the saponification and precipitation reactions.

Report suggestions:

Explain the lipids solubilization.

Explain the lipids saponification.

Discuss how we could analyse the fatty acids.