Originally Posted by redpanda
The icing not becoming violet is a clue that the acidity of the new Crisco is different. I think that the violet is less stable when alkaline (as opposed to acidic), but I could be mistaken. If I have time over the weekend (and a tub of violet coloring, I'll experiment. FUN!)
I can't find the original reference I saw for this several months ago, when somebody posted that their purple icing was turning blue.
I haven't had time to turn my kitchen into a lab, but I did a little more Googling. It appears that many of the red pigments are acid-sensitive--that is, they tend to fade out in the presence of higher acidity. Since violet is a mixture of blue and red pigments, that would mean that if the icing was more acid (than basic/alkaline), just the blue would come through. That explains why I haven't had a problem--according to my son's tests in his chemistry lab, our tap water has a very alkaline pH. I new there was a reason why I haven't bothered with bottled water in my icing lately.
So, I guess the solution would be to counteract the higher acidity of the new formula, but I'm not sure how best to do that.