I realize I'm too late for this to really be of any use right now, but I thought I'd go ahead and write it :-)
We're allergic to artificial food dyes around here, so I've had to get creative on colored foods. I have used a pkg of frozen blueberries, thawed it, and used the juice to dye white icing for a cake. You could use the juice to stain/dye anything lighter in color.
mama to Catherine (4) and Samuel (1)