Food tests - Required practical

Question 1

What is step 1 of this practical ?

Answer 1

Get a piece of food and break it up using a pestle and mortar

Question 2

What is step 2 of this practical ?

Answer 2

Transfer the ground up food to a beaker and add some distilled water

Question 3

What is step 3 of this practical ?

Answer 3

Give it a stir with a glass rod to dissolve some of the food

Question 4

What is step 4 of this practical ?

Answer 4

Filter the solution using a funnel lined with filter paper. This will get rid of the solid bits of food.

Question 5

What do carbohydrates include ?

Answer 5

Starch and sugars

Question 6

What are the 3 steps for Testing for starch ?

Answer 6

1) Make a food sample and transfer 5cm ³ to a test tube
2) Add a few drops of iodine and gently shake the tube.
3) If the sample contains starch the colour of the solution will change from browny-orange to black or blue-black.

Question 7

W\hat are 5 steps to use benedict’s test to test for sugars ?

Answer 7

1) Prepare a food sample and transfer 5cm ³ to a test tube
2) Prepare a water bath so that its set to 75°C
3) Add about 10 drops of benedict’s solution to the test tube using a pipette
4) Place the test tube in the water bath using a test tub holder leave it for 5 minutes.
5) If the food sample contains a reducing sugar the solution will change from blue to green, yellow or brick-red the colour depends on how much sugar is in the food

Question 8

When testing for sugar what does the colours blue, green, yellow and brick red Tell us ?

Answer 8

Blue - normal colour
green - small amount of sugar
Yellow - there is more sugar present
Brick-red - A lot of sugar present

Question 9

What are 3 steps to test for proteins ?

Answer 9

1) Prepare a sample of your food and transfer 2cm³ to a test tube
2) Add 2cm³ of biuret solution to the sample mix by gently shaking
3) If the food sample contains proteins the colour will turn from blue to purple

Question 10

What are 3 steps to test for lipids ?

Answer 10

1) Prepare food sample but don’t filter it transfer 5cm³to a test tube
2) Add 3 drops of Sudan III stain solution to test tube and gently shake.
3) If the sample contain lipids the mixture will separate into 2 layers the top layer will be bright red.