SC - What happened?

[Etain1263 at aol.com]

In a message dated 00-05-13 16:48:39 EDT, you write:

<< 
 2.  The color.  Pink.  Or purple.  Or brown.  Or bright purple.  It kept
 changing.  This didn't seem to have much to do with the changing strength of 
the
 vinegar flavor but I wasn't keeping tabs.  It seemed to mostly be getting
 darkerbrown as time went on but then abruptly went back to a lovely shade of
 purple and stayed that way.
 
 Ta,
 -M >>

You just discovered a "cub scout" use for red cabbage:  a ph indicator!  
Yes..it was the vinegar.  As the taste sharpened..the acid content 
increased..and your purple color changed accordingly (as a good little 
indicator should!)
  Now...WHY the acid "came and went"...my guess (and not a terribly scholarly 
one) is that you formed some sort of buffer that was changed as you cooked 
it..and it buffered the acid when it was active..and then released it when 
broken down by the heat.  But..I have no idea what chemicals are involved.

Etain