Food test - practical

• 1. Get the piece of food and break it up using a pestle 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 to get rid of the solid bits of food
• Benedict’s test to test for sugars 


  Test for reducing sugars in foods using the Benedict’s test:

  1. prepare food sample and transfer 5cm^3 to a test tube
  2. prepare a water bath so that it’s set to 75°
  3. add some Benedict’s solution to the test tube using a pipette
  4. place the test tube in the water bath using a test tube holder leave it in there for 5 minutes make sure the tube is pointing away from you
  5. if the food sample contains a reducing sugar will change from the blue colour to green, yellow or brick red- depends how much sugar is in the food
• iodine solution to test for starch 


  By:

  1. make a food sample and transfer 5cm^3 of your sample to a test tube
  2. then add a few drops of iodine solution and gently shake the tube to mix. If it contains starch will change from browny-orange to black or blue-black
• biuret test to test for proteins

  By:

  1. prepare a sample of your food and transfer 2cm^3 of your sample to a test tube
  2. add 2cm^3 of biuret solution to the sample and mix the contents of the tube by gently shaking it
  3. if the food sample contains protein will change from blue to purple
• Sudan III test to test for lipids

  by:

  1. lrepare a sample of the food you’re testing (don’t need to filter) transfer 5cm^3 into a test tube
  2. use a pipette to add 3 drops of Sudan III stain solution to the test tube and gently shake the tube
  3. Sudan III stain stains lipids if it contains lipids the mixture will separate out into 2 layers. top layer will be bright red if none of present no layer will form