Color Changing Cabbage on A Dash of Science.com

Color-Changing Cabbage Experiment

Did you know that you can change the color of red cabbage without using any dyes? Red cabbage gets its great purple color from anthocyanins. Anthocyanins, like most plant pigments, change color based on the pH of their environment. So when red cabbage is put into an acidic or basic solution it looses its characteristic “red” color.

This experiment is really easy. All you need is a red cabbage, baking soda, vinegar and about 30 mintues.

 

Materials

  • 1 cup of diced red cabbage
  • 2 cups water
  • 1 tsp vinegar
  • 1 tsp baking soda
  • pot and lid
  • several bowls

 

Method

1. Put water on the stove to boil.

diced cabbage on A Dash of Science.com

2.  Dice  enough red cabbage to fill approximately 1 cup.

boiling cabbage on A Dash of Science.com

3. Once the water is boiling, put in the red cabbage and simmer for 15 minutes.

strained cabbage on A Dash of Science.com

4.  Strain the cabbage to collect the colored water.

5.  Pour the cabbage water into three different containers. In one container add the vinegar and stir. In another container add the baking soda and stir.

 

Expected Results

cabbage juice colors on A Dash of Science.com

The colors look better in real life.

The originial cabbage water should be a purple-blue color. The acidic solution that has vinegar in it should look pink or red. The basic solution that has baking soda in it should be blue, turquoise or green.

 

Experiment Variations

colored cabbage on A Dash of Science.com

The texture changes too.

Change the actual cabbage color by boiling the cabbage in the acidic or basic solutions. Acidic solution: 100mL water and 20mL vinegar. Basic solution: 120 mL water and 1/4 tsp baking soda. There is a lot less water (only about 1/2 cup) so make sure the cabbage doesn’t scorch.

 

red cabbage pH indicator on A Dash of Science.com

Left to right the pH are: 1, 3, 5, 7, 8, 9, 10, 11, 13.
This was done in a lab that had stronger acids and bases.

Play around with the amount of vinegar or baking soda. The anthocyanins in red cabbage are very sensitive to pH changes. Because of this, red cabbage juice can be used as a pH indicator. You can tell the approximate pH of something by what color it turns cabbage juice.     CAUTION: do not mix the vinegar with the baking soda unless you want a mini volcano (another fun science experiment).

 

Other vegetables to experiment with: beets, carrots, spinach, and rice. Note: the pigments in carrots and rice don’t go into water well so do the first experiment variation method for those.

Food Pigment Acidic Color Neutral Color Basic Color
Red Cabbage anthocyanins pink purple turquoise
Carrots carotenoids light orange orange dark orange
Spinach chlorophyll olive green green kelly green
Beets betalains magenta red brown
Rice anthoxanthins white white yellow

 

Wrap Up

I had a lot of fun doing this experiment and some of the variations. I hope you do too. Let me know how it goes!

 

Images: Nathalie Dulex  and Supermartl

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