Food Tests

What are benedict’s test for?

Sugars

What are the iodine solution for?

Starch

What are the Biuret test for?

protein

What is Sudan III test for?

Lipids

What colour does starch change if its positive?

Brown-orange to blue-black

What colour does protein change if its positive?

blue to purple

What colour does lipds change if its positive?

bright red

Benedict’s practical

1. prapare a food sample and trasnfer 5cm³ to a test tube

2. prepare a water bath sp that it’s set to 75*c

3. Add some Beneditc’s solution to the test tube using a pipette

4. Place the test tube in the water bath using test tube holder and leave it in there for 5 minutes

5. make sure the tube is pointing away from you

6. if it is positive it’ll change from blue to green, yelloe, brick-red - depending on how much sugar is in the food.

Iodine solution test

1. make a food sample and transfer 5 cm³ of your sample to the test

2. Then add a fre drops of iodine solution and gently shake the tube will change colour.

Biuret test

1. Prepare a sample of your food and transfer 2cm³ of your sample to the test tube

2. add 2cm³ of biuret solution to the sample mix the contents of the tube by gently shaking it.