Practical Activities.docx

Practical Activities To test for Starch – Method Take sources rich in starch (Bread, potato, Pasta) As a control, take sources with no starch (Egg whites, Apple) Add a few drops of iodine solution to each substance. -In the foods where starch is present, the iodine solution turns from brown to blue-...

Practical Activities To test for Starch – Method Take sources rich in starch (Bread, potato, Pasta) As a control, take sources with no starch (Egg whites, Apple) Add a few drops of iodine solution to each substance. -In the foods where starch is present, the iodine solution turns from brown to blue-black. -In the foods where no starch is present, the iodine solution will stay orange-brown. To test for reducing Sugar – Method Pour a source of reducing, such as glucose solution or a colourless soft drink into a test tube. To act as a control, put an equal amount of water into a separate test tube. Add a few cm3 of Benedict’s Solution to each test tube and mix. Place both test tubes in a hot water bath and leave to stand for a few minutes. Results - The test tube containing the glucose plus Benedict’s solution turned from blue to orange/red, showing the presence of reducing sugar. - The test tube containing the water plus Benedict’s solution remained blue as it is a non-reducing sugar solution. Practical Activities Test for Lipids – Method Take sources rich in lipids (Butter or Vegetable Oil) As a control, take a substance with no lipid (Water) Rub each substance onto brown paper and leave to dry Results -The translucent stain caused by the water disappears when it has dried. -The translucent stain caused by butter/oil is permanent, showing lipid is present. Practical Activities To test for protein – Method Take a sample of food rich in protein (Egg white, Cheese, Chicken Breast) As a control take a food that does not contain protein (White Rice) Place the samples in two labelled test tubes Add biuret solution to each test tube and shake Results - The test tube containing protein turns from blue to purple - The test tube that does not contain protein remains blue