MadSci Network: Botany
Query:

Re: Does coating a plant's leaves with mayonnaise affect the leaf's pigments?

Date: Fri Feb 9 00:11:59 2001
Posted By: David Hershey, Faculty, Botany, NA
Area of science: Botany
ID: 979765495.Bt
Message:

Complete question:

I was testing transpiration on Coleus plants by coating the top and bottom 
of the leaves with mayonnaise along with other substances.  The pigments 
in the leaves of that plant changed color.  The yellow disappeared and the 
green part in the leaves grew darker after the mayonnaise was applied.

It was within about 6 hours that the leaves turned.  The light purple turned
almost to a black and the light green changed into a dark green.  I repeated it
with another plant, and the same thing happened.

Answer:

Mayonnaise contains vegetable oil, egg, and vinegar. The vinegar is acid so it 
is likely that the anthocyanin pigments in the coleus leaf are changing color 
due to the acid pH. You might try just using vinegar to help confirm that as 
the cause. The vegetable oil may or may not be needed to solubilize the plant 
membranes to allow the vinegar to enter.

A classic, and very popular, school experiment uses the pH-induced color change 
of anthocyanins in red cabbage leaves or other plant materials as a pH 
indicator. To find lots of sites, use a search engine like google.com and 
search for red cabbage pH.  

Reference


Red Cabbage pH Indicator


Red Cabbage





Response:


Re: Does coating a plant's leaves with mayonnaise affect the leaf's pigments?

Greetings - Your question was not submitted to the
MadSci Network for the following reason:

Please provide further specifics. As it stands it would be
difficult for us to find an answer to your question. Questions may
be resubmitted via http://www.madsci.org/submit.html

Hi Jenny - It would help to know the time course of how/when
the pigments changed - was it a matter of days, a week, or more?
Cheers..

	Lynn Bry, Admin MadSci Network


_______________________________________________________________
I was testing transpiration on Coleus plants by coating the top and bottom 
of the leaves with mayonnaise along with other substances.  The pigments 
in the leaves of that plant changed color.  The yellow disappeared and the 
green part in the leaves grew darker after the mayonnaise was applied.


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