Food tests practical

Question 1

How do you prepare a sample

Answer 1

Break up the food using a pestle and mortar
Transfer to a test tube and add distilled water
Mix the food with the water by stirring with a glass rod
Filter the mixture using a funnel and filter paper, collecting the solution
Proceed with the food tests

Question 2

What test would you use to test for sugar(reducing)

Answer 2

benedict’s solution

Prepare food sample and transfer 5cm cube to test tube

prepare water bath that’s set to 75 degrees

benedict’s solution to test tube(10 drops) using pipette

place test tube in water bath using test tube holder and leave for 5 min. Make sure tube points away from you

normal colour blue to green , yellow or brick red

Question 3

Starch is tested using what

Answer 3

iodine solution

5cm cubed

add few drops of iodine solution and gently shake to mix contents.

If contains starch solution from browny-orange to black or blue-black

Question 4

test for proteins

Answer 4

Biuret test

prepare sample of 2cm of your sample to test tube

add 2cm of biuret solution to sample and mix contents of tube by gently shaking

blue to purple

Question 5

What is Lipids

Answer 5

Sudan III test prepare a sample no need to filter

transfer 5cm of food to test tube

add 3 drops of Sudan iii stain solution to test tube gently shake

Sudan iii stains lipids mixture will separate out into 2 layers top layer will be bright red