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Why Do Greens Turn Brown? (page 2)

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Author: Cy Ashley Webb

Experimental Procedure

Experiment #1
  1. Cut up some sturdy romaine leaves.  Put them in a place where they will not be disturbed for two days.  
  2. Tear some sturdy romaine leaves.  Try tearing along the ridges of leaves and wherever the tear seems most natural.  Put the torn leaves in place where they will not be disturbed for two days.
  3. Leave some untouched romaine leaves undisturbed for two days.  These are your controls.
  4. Repeat steps one, two, and three with fragile basil leaves.
  5. Inspect your leaves at six hours, 12 hours, 18 hours, 24 hours, 36 hours and 48 hours.  Which has browned the most?  Is there a difference between the controls and the other leaves?  Is there a difference between the cut and torn leaves?  What about between the basil and the romaine leaves?  Write up your observations.  Take pictures.
Experiment #2
  1. Lightly dress some red lettuce leaves with vinegar.  Any kind of clear vinegar will do.  Leave the vinegar-dressed leaves on white paper towels.  Leave some undressed leaves on white paper towels as controls.  
  2. Inspect the lettuce leaves at twenty minutes, a half hour, 1 hour, and 2 hours.  Look at the paper towels closely.  Is there any evidence of paper towels getting stained by pigments leaking out of damaged cells?
  3. Inspect a portion of the control leaves and the vinegar-soaked leaves under a microscope.  Draw what you see.
Experiment #3
  1. Lightly dress some lettuce leaves with vegetable oil (any kind of lettuce work well for this).    Dress some other lettuce leaves with water.
  2. Inspect the lettuce leaves immediately after dressing them, and at 10 minutes and 20 minutes Do the water and oil bead up or spread out on the leaves?  What happens to the texture of the leaves?
  3. Inspect the leaves under a microscope.  Using a pin, poke a hole into one of the oil-soaked leaves and watch carefully under the microscope for several minutes.  What do you see?
  4. Write up your observations.  Take pictures!

Bibliography

  1. The Curious Cook by Harold McGee
  2. McGill Office for Science and Society "Why Does Lettuce Sometimes Turn Brown?"
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