LIPIDS PROPERTIES

OBJECTIVES:

• Know the solubility of lipids
• Identify lipids
• Emulsion and effect of detergent

MATERIAL:

• Test tube rack
• 250mL beaker
• Water
• 6 test tubes
• Cellulose paper
• Dropper
• Scissors
• Glass rod
• Olive oil
• Soap
• Milk with different fat content: Full-cream, semi-skimmed and soy milk
• Petroleum ether
• Ethanol
• Sudan III

PROCEDURE:

Solubility of lipids:

1. Put 3 test tube in a test tube-rack, each one with a different mark
2. Put water in one test tube, ethanol in other test tube and ether in other. 
3. Put 1 drop of oil in each test tube
4. Observe the results 

                                     

Lipids identification:

   Translucent mark:

1. Cut one piece (10x10cm) of cellulose paper
2. Put 1 drop of water in a part of the squared piece. You will see a lucid spot.
3. Put 1 drop of olive oil in an other part of the squared piece of cellulose paper. You will see a translucent spot.  

                                   

   Sudan III dye: Sudan III is a red fat-soluble dye that is utilized in the identification of the presence of      lipids, triglycerides and lipoproteins in liquids.

1. Prepare three test tube: Each one with milk with different fat content (M1, M2, M3) 
2. Add 2 drops of Sudan III and observe the results.

                                                                       

Emulsion and effect of detergent:

1. Take a 250mL beaker and put 100mL of water
2. Add 1mL of olive oil. With a glass rod stir the mixture vigorously and let it satnd for a few minutes
3. Observe what is happening
4. Add 2 drops of soap and stir the mixture again. Let it stand for a few minutes and notice the differences between both mixtures

                                                                   

RESULTS:

Solubility of lipids: 

In the test tube with water, the oil didn't mix with it.
In the test tube with ethanol, the oil is more dense than ethanol
In the test tube with ether, the oil mix with it
Lipids identification:
   Translucent mark:
In the part of the paper with water you will see a lucid spot and in the part of the paper with olive oil you will see a translucent spot.  
  Sudan III dye:

• Semi-skimmed milk: The solution stain soft red
• Full-cream: The solution stain reddish
• Soy juice: The colour doesn't change

Emulsion and effect of detergent:
When in the beaker only there are water and oil, when you try to mix them, they didn't blend but when you put soap in the mixture, the soap capture the oil.

QUESTIONS:

1.  From your observation, which compounds can dissolve lipids? The compound that can dissolve lipids is ethanol.
2. Do the oil and water mix? What can you conclude about the polarity of the oil if you know that water is polar? No, they don't. I can conclude that the polarity of the oil is non-polar and more over water can't dissolve lipids.
3. Why is liquid the olive oil at room temperature? Because has a low melting point 
4. Why does a lipid leave a translucent spot on paper? Because is a fatty acid
5. Which type of milk contains more lipids? Why? Full-cream is fattier than the others so it contains more lipids
6. Did the oil and water mix when you added the soap? Yes, it did.