Test

Question 1

How do you prepare a Food sample

Answer 1

• Get food & break up using a mortar a pestle
• Put into beaker with distilled water
• Stir with glass rod until most of it dissolves
• Filter out solution using funnel lined with filter paper to get rid of solid bits of food we do not need

Question 2

Benedicts test (reducing sugars)

Answer 2

-Prepare food sample
- Transfer 5cm^ of sample to a test tube
- Prepare water bath and set it to 75 ‘C
- When ready add 10 drops of Benedicts solution to test tube & place in water bath for 5 minutes
- If reducing sugars present solution turns Green, Yellow or even Brick Red dependant on concentration
- If no reducing sugars present no colour change and will stay blue

Question 3

Iodine test (Starch)

Answer 3

-Take 5cm^3 of food sample
-Add a few drops of Iodine solution
-Turns solution Brown/Orange colour
-Gently shake tube
- If sample contains starch solution will change from brown/orange colour to a blue black colour
- If no colour change solution stays same colour

Question 4

Biuret test (Protiens)

Answer 4

• Add 2cm^3 of Sample to your test tube
• Add 2cm^3 of Biuret solution to sample
• This turns it Blue
• Shake gently
• If sample contains protein it will turn a pink or purple colour

Question 5

Sudan III test (Lipids)

Answer 5

-Prepare 5cm^3 of food sample (Not filtered) and put into a test tube
- Add 3 drops of Sudan III stained solution to test tube
-Gently shake
-If positive The Sudan III stain binds to the lipids.
- A red-stained oil layer forms on the surface of the liquid.
- If no Lipids present
No separate red layer forms.
The solution remains evenly mixed without a distinct oil layer.