Food Tests

Question 1

How to get food samples for tests

Answer 1

1) Get food crush it up then put it in a beaker with water and pestle and stir it with a glass rod until it dissolves

2) Then get a funnel that’s lined with filter paper then take out the solution to get rid of the solid bits we dont need

Question 2

Benedict’s test (sugars)

Answer 2

•Reducing
•Non-Reducing

1) We transfer 5cm of food solution to a test tube

2)Then put a water bath to 75* celsius when

3) When the water bath is ready add 10 drops of Benedict’s solution to the test tube

4) Then put the test tube in the water bath for 5 minutes (for safety use test tube holder and point tube away from you or anyone else)

Then if no reducing sugars are present the solution will stay blue but if there is reducing sugar present it will turn to the colours green/yellow/brick red depending on the concentration

Question 3

Starch test
(Iodine test)

Answer 3

1) Get 5cm of food sample and add a few drops of iodine solution which will turn the soloution

2) Then give it a shake and if starch is present it will turn from orange to blue/black

Question 4

Biuret test (test for protein)

Answer 4

1) Add 2cm of food sample to a test tube

2) Then add 2cm of Biuret’s soloution to the test tube with the food sample in

3) Then give it a gentle shake

And if protein it present it will change from blue to purple/pink

Question 5

Sudan III (lipids test)

Answer 5

1) 5cm of food sample in a test tube (doesn’t need to be filtered)

2) Then add 3 drops of Sudan III to the test tube and gently shake it

If the lipid is present it should get stained leaving a red ring this is because lipid separates from water