Practical Flashcards
1
Q
What is Biuret’s test for
A
Proteins
2
Q
What is Benedict’s test for
A
Reducing sugar
3
Q
What is Iodine test for
A
Starch
4
Q
What is ethanol emulsion test for
A
Fats
5
Q
How to carry out Biuret’s test
A
- Add 1cm^1 of sodium hydroxide solution to 2cm^3 of food solution
- Shake thoroughly
- Add 1% copper(II)sulfate solution drop by drop, shaking after each drop until colour change observed
6
Q
How to carry out iodine test
A
- Place food substance or solid food onto white tile
- Add a few drops of iodine solution to substance and observe colour change
7
Q
How to carry out Benedict’s test
A
- Add equal volume of Benedict’s solution to 2cm^3 of food solution in a test tube
- Shake mixture thoroughly
- Place test tube in a boiling water bath for 5 minutes
- Observe precipitate formation and colour changes
8
Q
How to carry out ethanol emulsion test
A
- Add 2cm^3 of ethanol to 2cm^3 of food solution in a test tube
- Shake mixture thoroughly
- Decant ethanol mixture into another test tube containing 2cm^3 of water
9
Q
Observations and conclusions if no reducing sugars present
A
- Solution remained blue
- No reducing sugars present
10
Q
Observations and conclusions if little concentration of reducing sugars present
A
- Green precipitate formed
- Little concentration of reducing sugars present
11
Q
Observations and conclusions if moderate concentration of reducing sugars present
A
- Yellow precipitate formed
- Moderate concentration of reducing sugars present
12
Q
Observations and conclusions if large concentration of reducing sugars present
A
- Orange or brick-red precipitate formed
- Large concentration of reducing sugars present
13
Q
Observations and conclusions if proteins present
A
- Violet colouration observed
- Proteins present
14
Q
Observations and conclusions if proteins absent
A
- Solution remained blue
- Proteins absent
15
Q
Observations and conclusions if starch present
A
- Blue black colouration observed
- Starch present
