Page 8 - exemple
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5 Identification test for mineral substances
a- Identification of water in food
Heat a test tube containing a piece of bread.
We observe the condensation of water vapor
on the cold extremities of the tube.
Water
b- Identification of chlorides in
food
Mix bread with water for few hours. Filter the
mixture.
Add few drops of silver nitrate. We observe the
formation of a white precipitate of silver
Doc 6- Identification of water in a foodstuff.
chloride.
Doc 7- Identification of mineral salts: chlorides.
Complex foods are formed of simple molecules (organic or mineral).
Probing of activity 2
1- Describe a test that allows us to identify the presence of proteins or peptides in milk or
bread.
2- By referring to document 2, what is the level of glucose indicated by the glucose paper strip?
3- Do apples and grapes contain a reducing sugar? Justify the answer by performing the
appropriate test.
4- Propose a test that determines the presence or absence of starch in “labneh”.
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