Topic 2 Food Tests #

Question 1

How to prepare the food sample

Answer 1

1) get a piece of food and break it up using a pestle and mortar
2) transfer ground up food to a beaker and add some distilled water
3) stir with glass rod to dissolve the food
4) filter the solution using funnel lined with filter paper to get rid of solid bits of food

Question 2

What does Benedict’s solution test for

Answer 2

Reducing Sugars

Question 3

Benedict’s test steps (1-3)

Answer 3

1) prepare a food sample and transfer 5cm3 to a test tube
2) prepare a water bath set to 75°c
3) add 10 drops of Benedict’s solution to the test tube using a pipette

Question 4

Benedict’s test steps (4-5)

Answer 4

4) place test tube in the water bath and leave it there for 5mins
Point test tube away
5) if food sample contains reducing sugar solution will change from the normal blue - green - yellow - brick red

Question 5

What does iodine solution test for

Answer 5

Starch

Question 6

Iodine test for starch steps 1-2

Answer 6

1) make a food sample and transfer 5cm3 into a test tube
2) add a few drops of iodine solution and gently shake to mix
If sample contains starch solutions will change from browny orange - blue/black

Question 7

What does biuret test for

Answer 7

Proteins

Question 8

Biuret test steps 1-3

Answer 8

1) prepare food sample and transfer 2cm3 of your sample to the test tube
2) add 2cm3 of biuret solution to the sample and mix by gently shaking it
3) if the food sample contains proteins it will change from blue - purple

Question 9

What does Sudan III test for

Answer 9

Lipids

Question 10

Sudan III test steps 1-3

Answer 10

1) prepare food sample but don’t filter it
Transfer 5cm3 into the test tube
2) use pipette to add 3 drops of Sudan III stain solution to the test tube and gently shake
3) Sudan III stain solution stains lipids
If the sample contains lipids the mixture will split into two layers. The top layer will be bright red