I am a Girl Scout leader. One of the girls in my troop is affected by artificial red and yellow food dyes. I want to prepare or purchase icing for them to do a team building cake decorating activity. Is there a brand of natural food color that could be used to color white icing that works well and does not affect taste? If so, where do I get it? I have major regional grocery stores, walmart/target, trader joes, michaels, and with more effort whole foods or fresh thyme.

I plan to confer with the mom, but I would like to already have a plan..... of course, my first plan may be to have her bring the icing. : )

Thanks for your help!