RE: HYB/Science-Pigment Extraction

In terms of solvents, waater is a polar solvent, and oil is a non polar solvent. Alcohol has a molecular structure that alows it to bind polar molecules on one end and non polar on the other end, so can disolve chemicals otherwise only soluble in oil or only soluble in water. The term polar versus non-polar has to do with the chemical stucture of the molecules and has to do with how they orientate in regards to each other etc ( very simplified explination, for more see introductory chemistry books, University level). Thus what is disolved in alcohol is either a water soluble or an oil soluble pigment. Mixing a bit of oil with the alcohol ( one with a good difference in specific gravity) and shaking with help separate these pigments as any oil soluble pigment will migrate to the oil and any water based pigment will remain in the alcohol.

Alcohol penetrated tissues a bit better then water and first extraction doesn't always remove all of the pigment. Thus the blue is likely a more dilute solution on the anthocyanin that is in a heavier concentration in the water, perhaps modified by some oil based pigment included. 
For the blue , separate out the oil based pigment first. Then dilute some of the purple pigment to the same density, and then the  blue and the purple will look the same 

Chuck Chapman

Date: Mon, 16 May 2005 12:05:46 -0400
From: Linda Mann <lmann@volfirst.net>
Subject: [iris] HYB: pigments - Stunning

STUNNING is always eyecatching here - white ground with bright red fall
spot.

hot water extraction - typical purple
isopropyl alcohol extraction - gorgeous blue shade
safflower oil extraction - slight amount of yellow

This is the first time I've gotten blue - could this be pallida blue
(delphinadin?).  All the blue flowers I've tried so far (not many) have
yielded purple extract.

I've gone back to safflower oil - much faster separation than paraffin
oil/isopropyl combination,  I can pour it down the sink when I'm done,
plus less worry of burning the house down when it spills.
- --
Linda Mann east Tennessee USA zone 7/8


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