Food Tests Required Practical

Question 1

How to test for starch

Answer 1

Place a small amount of food mixture into a test tube
Add a few drops of iodine solution to the food into the test tube
Reddy brown iodine solution turns blue-black if starch is present
Repeat steps 1-3 for other types of food
Record your result in results table

Question 2

How to test for sugar

Answer 2

Place a small amount of grounded food into test tube
Add enough Benedicts solution to cover the food
Place the test tube in a warm water bath for 10 minutes
Blue Benedicts solution turns brick red on heating if sugar such as glucose is present
Repeat steps 1-4 for other types of food
Record all your results in a results table

Question 3

How to test for lipids

Answer 3

Place a small amount of food into a test tube
Add three drops of Sudan III stain solution/ethanol to the test tube
Shake the test tube and leave for one minute
Record all your results in a results table

Question 4

How to test for protein

Answer 4

Place a small amount of food in a test tube
Add 1cm³ of Biuret reagent OR sodium hydroxide solution and a few drops of copper sulfate solution
Blue Biuret reagent turns purple if protein is present
Repeat steps 1-3 for other types of food
Record all your results in a results table

Question 5

Prep for all tests

Answer 5

Grind a sample of food, using a pestle and mortar add 10 cm³ of water

Question 6

Safety

Answer 6

Do not eat any of the food, wear chemical splash-proof eye protection
Biuret: irritant
Sodium hydroxide: irritant
Ethanol: highly flammable, keep away from naked flames
Iodine: harmful, avoid contact with skin