1. LABORATORY ANALYSIS
PROTEINS
During a lesson in the laboratory we have analyzed some
aliments products in order to verify the presence or the lack
of proteins.
ISISS G.B.
2. 1
We have analyzed some diary products such as: milk, butter and
yogurt.
For this verification we use the biuret test that consists of mixing
food with two solutions
(a solution with sodium hydroxide at 10% and a solution with
copper sulfate at 10%).
3. The experiment starts:
•we melt the albums with water in a test tube, having a protein
solution
•we add 20 drops of sodium hydroxide and then 10 drops of
copper sulfate.
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4. We notice immediately that the mixture takes a purple color
that indicates us the presence of polypeptides, so proteins.
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5. We do the same process with milk, butter and yogurt and we
notice that all of this diary food make the reaction, in fact the
mixtures take a different shade of purple for each food.
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6. To verify that the reaction happens only in presence of proteins, we
do a blank solution and we notice that in absenceof
proteins, the reaction doesn't happen so the experiment successes.
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7. We have studied that some substances melt only in fats such as
Sudan III.
To do this experiment we have used these ingredients:
• 2 test tube • reactive Sudan III
• water • a dropper
• seed oil
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LIPIDS
8. We put in a test tube 10 ml of water and we add 10 drops of
Sudan III. We close the test tube and we shake energetically
and after that we leave rest it.
We put in an other test tube 10 ml of water, 10 drops of seed oil and
10 drops of Sudan III. We close the test tube and we shake it
energetically so we leave rest it.
After 10 minutes we can observe that in the first test tube(that
contains water and the reactive) the situation doesn't vary while in7
