What is the 1st step of the food test practical?
Take the food sample and grind this with distilled water using a mortar and pestle. We want to make a paste.
What’s the 2nd step of the food test practical?
Transfer the paste to a beaker and add more distilled water. Stir so that the chemicals in the food dissolve in the water.
What is the 3rd step of the food test practical?
Filter the solution to remove suspended food particles.
How to test for starch?
We place our food solution in a test tube
We add a few drops of iodine solution which is yellow
If starch is present it will turn blue/blck
If it isn’t it’ll stay orange
How to test for sugars?
We place the food solution in a test tube
Add 10 drops of Benedict’s solution which is blue
Place this test tube in a beaker and half fill the beaker with boiling water from the kettle
Leave for 5 minutes
If sugar is present it’ll turn green(if there is little sugar) yellow(if there is more sugar) brick red ( if there are high amounts of sugar)
If sugar isn’t present then it’ll stay blue
How to test for lipids?
We add the food solution to a test tube
Add a few drops of distilled water and ethanol
Gentle shake
If lipids are present white cloudy emulsion forms
If lipids aren’t present it’ll stay colourless
How to test for protein?
We add 2cm cubes of food solution to our test tube
Add 2cm cubed biuret solution which is blue
If protein is present it’ll turn lilac/purple
If protein isn’t present it’ll stay colourless