Required practical: Food test

What is the 1st step of the food test practical?

1. 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