Food tests required practical

Question 1

How do you prepare the food sample

Answer 1

1. grind with a pestle and mortar to make a paste
2. transfer to beaker and add more distilled water
3. filter solution to remove suspended food particles

Question 2

What chemical is used to test for starch, what colour is it

Answer 2

iodine
orange

Question 3

What colour does iodine turn when starch is present

Answer 3

present- blue/black

Question 4

How do you test for sugars

Answer 4

place drops of benedicts solution and then place in a water bath and leave for 5 mins to notice a change in colour

Question 5

What chemical is used to test for sugar, what colour is it

Answer 5

Benedicts solution
blue

Question 6

What colour/s does benedicts solution turn when sugar is present

Answer 6

green there’s a small amount present
yellow there’s more present
brick red there’s a lot present

Question 7

What chemical is used for testing protein and what colour is it

Answer 7

biuret solution
blue

Question 8

What colour does biuret solution turn when protein is present

Answer 8

lilac/purple

Question 9

How do test for lipids

Answer 9

grind using pestel and mortar with distilled water but do not filter the solution
in a test tube add a few drops of distilled water and ethanol and gently shake

Question 10

What does a positive test for lipids look like

Answer 10

when shaken a cloudy emulsion will form