Color Changes of Chlorophyll in Response to Changes in pH

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Color Changes of Chlorophyll in Response to
Changes in pH
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Introduction

• In the subsequent slides the background color of
  the slide represents the color the pigment
  assumes under various conditions of pH.
• Under more or less neutral conditions,
  chlorophyll has its normal vegetable green color
  (think of raw green beans or broccoli)

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Chlorophyll
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Acidic conditions

• Under acidic conditions, the magnesium atom
  (Mg2) is lost and the color changes to the
  characteristic pheophytin olive green color.

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Pheophytin
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Alkaline conditions

• Under alkaline conditions the methyl and phytyl
  esters are removed, producing chlorophyllin which
  is a bright green color.

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Chlorophyllin
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Chlorophyllase

• Other reactions, mediated by the enzyme
  chlorophyllase, may result in changes in the
  pigment, even under conditions of frozen storage.
• This is why such vegetables (green beans,
  broccoli, etc.) are blanched (put briefly in
  boiling water) before preservation by freezing.
  This destroys the enzyme activity.