Carbohydrates by yurtgc548


									Organic Testing Lab

   There are macromolecules (organic
    compounds) in certain foods

   Chemical indicators will tell us there
    are organic compounds in some, or
    all, of the samples
   Test tubes
   Test tube rack
   Masking tape
   Hot plate
   Iodine solution
   Sample A
   Sample B
   Sample C
   Distilled water
   Paper towels
   600 mL beaker
   Benedict’s solution
   Biuret solution
   A paper bag
        Procedure-Starch Test
   Put on a lab coat, goggles and gloves.
   Sugars and starches are two common types of
    carbohydrates. To test for starch, label 4 test
    tubes A, B, C, and Water. Fill the 4 test tubes
    with 2 mL of the substance indicated on the label
    on the test tube.
   Add 5 drops of iodine solution to each test tube.
    Iodine will change color from yellow-brown to
    blue-black in the presence of starch.
   Gently shake the contents of each test tube. BE
    CAREFUL! In Starch Test, record color changes
    and write present or not present next to those
    substances testing positive for starch.
   Wash the test tubes thoroughly.
         Procedure-Sugar Test
   For the sugar test, half fill the beaker with tap water. Heat
    the water to a gentle boil. BE CAREFUL!
   While the hot water bath is heating, fill each cleaned test
    tube with 2 mL of the substance indicated on the masking-
    tape label. Add 10 drops of Benedict’s solution to each test
    tube. When heated, Benedict’s solution will change color
    from blue to green, yellow, orange, or red in the presence of
    a single sugar, or monosaccharide.
   Gently shake the contents of each test tube.
   Place the test tubes in the hot-water bath. Heat the test
    tubes for 3 minutes. WITH THE TEST TUBE HOLDER,
    remove the test tubes from the hot-water bath and place
    them back in the test-tube rack. In the Simple Sugar Data
    Table, record any color changes and place an + next to any
    substances that test positive for a single sugar.
   When the test tubes have cooled, wash them thoroughly.
      Procedure-Protein Test
   Put 2 mL of the appropriate substance in
    each labeled test tube. Add 5 drops of
    Biuret reagent to each test tube. BE
   Gently shake the contents of each test
    tube. BE CAREFUL! Biuret reagent
    changes color from blue to violet in the
    presence of proteins.
   Fill in Protein Data Table
   Wash the test tubes thoroughly
         Procedure-Lipid Test
   Divide a piece of brown paper into 4 equal
    sections. In each section, write the name of the
    one test substance.
   In each section, rub a small amount of the
    unidentified food onto the brown paper. Rub the
    food until a “wet” spot appears on the paper.
    With a paper towel, rub off any excess pieces of
    food that may stick to the paper. Set the paper
    aside until the spots appear dry- about 10
   Hold the piece of brown paper up to a bright light
    or window. You will notice that some foods leave
    a translucent spot on the brown paper. The
    translucent spot indicates the presence of lipids.
   Fill in Lipid Data Table

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