Cabbage pH Indicator
     The purple color, an anthocyanin, in purple cabbage 
    is a handy pH indicator. 

    It turns pink in the presence of acid,
    and blue to green with a base.

    To use it to determine pH in your experiments, 
    you must first extract the color into water. 

    Here is how to do it.
 
Recipe for Cabbage pH Indicator 
  

Ingredients and Materials 

  • A head of red cabbage
  • 1-2 quart pot with lid
  • distilled water
  • strainer
  • jar or bowl
  • white coffee filters (optional for indicator paper)
Procedure 
  • Cut up a head of purple cabbage and place it in a pot. 
  • Add water and cover with a lid. 

    • (Distilled water is best. Tap water has dissolved salts which may interfere with your experiment.)
  • Simmer for 15-20 minutes. 
  • Strain the liquid and cover or place it in a closed container. (Canning jars work well)
  • Store in the refrigerator. 
This indicator solution can be used by adding it to solutions that you want to test. 
    A blue or green color indicates a basic solution, 
    while a red color indicates an acid solution.
To make an indicator paper: 
  • Dampen white coffee filters with the cabbage indicator solution.
  • Allow the filter paper to dry.
This indicator paper can be used to test the pH of solutions. 
You may want to cut the treated filter paper into strips for some experiments. 
 
 
© 1996, 1997 Norman & Globus, Inc. All rights reserved. No part of this material may be reproduced, translated, transmitted, framed or stored in a retrieval system for public or private use without the written permission of the publisher.