PROTEIN IDENTIFICATION

INTRODUCTION:
Biuret's test is a chemical test udes for detecting the presence of peptide bonds. Polypeptides as proteins, are chains of amino acids link together by peptides bonds.
A peptide bond can be broken by hydrolysis. In organisms, protein molecules called enzymes facilitate the process.

OBJECTIVES:
1.Identify peptide bonds.
2.Compare protein concentration in different foods.

MATERIALS:
-7x250mL beaker
-5 test tubes
-Test tube rack
-6x10mL pipet
-Mortar
-Glass marking pen
-Gloves
-Goggles
-Milk
-Rice Milk
-Egg
-Potato
-Distilled water
-NaOH 20%
-10 drops of CuSO

PROCEDURE:
We are going to determine protein concentration in some foods: milk, rice milk, potato and eggss.
1.Add 100mL of distilled water to each 250mL beaker.
2.Label them with M (milk), RM (rice milk), EW (egg white), EY (yolk) and P (potato).
3.Separate the egg white and the yolk in another beaker.
4.Smach the potato in a mother and add some amount of the smashed potato to the P beaker.
5.Add 10mL of a dispersion of each food to the indicate beaker. Calculate the final concentration. All the groups will use the same dispersion from the beakers.
6.Prepare 6 test tubes and label the name.
7.Add 2 mL of the every food dilution of each beaker.
8.Add 2mL of 20%NaOH dissolution.
9.Shake gently and add 5 drops of CuCO in each tube. Allow the mixture to stand for 5 minutes.
 
CuCo                      NaOH
10.Note any colour change. Remember that proteins will turn solution pink or purple.
11.Compare the test tube.

RESULTS:
Potato: negative
Yolk: positive
Egg White: positibe
Rice milk: negative
Milk: positive

	Egg white	Yolk
PROTEINS	11	17,5
LIPIDS	0,2	32,5

LIPIDS PROPERTIES

INTRODUCTION:
Lipids are a heterogeneous group of compounds synthesized by organisms that are present in all biological tissues.

OBJECTIVES:
1.Test the solubility of lipids
2.Identify lipids in liquids compounds
3.Understand what are an emulsion and the effect of detergent

MATERIALS:
-3 test tube rack
-250mL beaker
-Water
-6 test tubes
-Cellulose paper
-Dropper
-Scissors
-Glass rod
-Olive Oil
-Soap (detergent)
-Milk with a different fat content: full-cream, semi-skimmed and skimmed milk
-Petroleum ether
-Ethanol
-Sudan II

PROCEDURE:
Solubility of some lipids:
1.Clean and dry three test tube.
2.Label as W (water), E (ethanol) and PE (ether).
3.Add 3 drops of oleic acid to 3 small test tube.
4.Add 1mL of water in the first test tube.
5.Add 1mL of ethanol in the second test tube.
6.Add 1mL of petroleum ether in the third test tube.
7.Shake carefully each test tube and record solubility and observations in your worksheet.

Lipids identification:
8.Cut two pieces (10x10cm) of cellulose paper.
9. Put 1 drop of water in the first squared piece. You will see a translucent spot.
10.Wait for a while and observe what is happening.
11.Put 1 drop of olive oil in the second squared piece of cellulose paper. You will see a translucent spot.
12.Wait for a while and observe what is happening.

SECOND PART: 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 in liquids.
13.Add 5mL of destilled water.
14.Add 2mL of oil.
15.Add a few drops of Sudan III.
16.Create the dye with. 10mL of Sudan III with a spatula, 20mL of ethanol and 6 drops of destilled water.

Permanent emulsion:
17.Take a 250mL beaker and put 100mL of water.
18.Add 1mL of olive iol. With a glass rod stir the mixture vigorously and let it stand for a few minutes.
19.Make note og what is happening.
20.Add 2 drops of soap and stir the misture again. Let it stand for a few minutes and notice the differences between both mixtures.