Beverly Erlebacher bae at
Fri Feb 9 18:19:22 EST 1996

In article <4fdjsn$je0 at> clanks at (John Clancy ) writes:
>i'm doing a phase two of a science fair project on anthocyanins, a
>flavonoid found in roses, red cabbge and african violets.  i read that
>they can change the plant's color when subjected to acids or bases, but
>my results last year were inconclusive...this year, i'm doing a better
>job, but i really don't have enough data on anthocyanins; i guess
>they're pretty obscure.
>if anyone can help me i'd really appreciate it.

Many purple pigments in plants are anthocyanins.  In general, they
are more red in acid solutions, and blue in basic solutions.  You
can observe this for yourself by taking some water from cooking 
red cabbage or beets, and observe the color change when you add
vinegar or baking soda.

To change the color of the plant (or its flowers), you will have to
change the pH of the solution the anthocyanins are in within the plant
cell.  This may well kill the plant!

It might be an interesting and attractive science fair project to extract
anthocyanins from several different plants, and use paper chromatography
to determine how many different bands different plants show, which are the
same or different between different species, and at what pH different forms
of anthocyanin show color change.  You could even make up a pH test kit
using extracts from various plants.

You may want to use alcohol to extract the anthocyanins.  Some good sources
are beets, red cabbage, red forms of coleus and red-leaved forms of other
ornamental plants.

The original work that led to the development of chromatography was done
by a woman in England who was interested in flower pigments.  She separated
them on long pieces of paper suspended over a stairwell.  The chemists who
developed chromatography received a Nobel prize for their work in the 1950's.

Beverly Erlebacher
Toronto, Ontario Canada

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