Food Tests- Experiment

Question 1

How do you prepare a food sample?

Answer 1

1) Get a piece of your food and break it up using a pestle and mortar
2) Transfer the ground up food to a beaker and add some distilled water
3) Give the mixture a good stir with a glass rod to dissolve some of the food
4) Filter the solution using a funnel lined with filter paper. This will get rid if all the solid bits of food

Question 2

What is the test for presence of starch?

Answer 2

.Place a small amount of food on a spotting tile

.Add a few drops of iodine to the food sample

.If the colour changes from yellow-red to blue-black, starch is present.

Question 3

What is the test for presence of sugars?

Answer 3

.Place a small amount of the food in a test tube

.Add a few drops of Bendict’s solution to the food sample

.Heat the test tube in a warm water bath

.If the colour changes from blue to brick red then sugars are present

Question 4

What is the test for presence of protein?

Answer 4

.Place a small amount of the food into a test tube

.Add 1cm3 of Biuret solution to the food sample

.If the colour changes from pale blue to purple, protein is present

Question 5

How do you test for the presence of fats?

Answer 5

.Place a small amount of the food into a test tube

.Add a few drops of ethanol to the solution

.Shake the test tube and leave for one minute

.Pour the ethanol into a test tube of water

.A cloudy white layer will appear on top of the water if fats are present

Question 6

List some safety precautions

Answer 6

.Do not eat any of the food, be aware of people who may have food allergies. Wear eye protection when using chemicals

.Biuret reagent is an irritaint, enthanol is highly flamable, keep away from naked flames, Iodine solution is harmful. Water in the water bath will be hot