This one time last summer I decided to take on a multi layer rainbow cake using all natural food coloring which I made in my kitchen. I tried all kinds of different ways to make my colors - carrot juice for orange (didn't work), cabbage for blue (sort of worked), steamed run off of beet (worked great!), turmeric (worked great tasted weird!).
I ended up making my primary colors and then mixing them to get the full spectrum:
1. a very faint blue by boiling chopped red cabbage in water and then adding baking soda to the water to make it blue;
2. a nice pink from the water of simmered beet
3. a decent yellow from Turmeric powder simmered with water.
I added each of these in a slow steady stream to their own respective bowl of white buttercream frosting, saving some of each to mix together to make orange and green.
All but the beet pink faded after 1 day. The cake, however, looked great and was delicious! Here is a little slide show of my icing adventures and the final Mermaid Cake product.
It was so fun making this mermaid cake! If only the event for which it was made did not get canceled the following day and I had not had to take huge chunks of cake bar to bar to make sure it was properly enjoyed. Oh well!
I will leave you with a wonderful find that I made at this year's Winter Fancy Food Show in SF - I found new natural food coloring! These ladies from Bend, Oregon figured out a chemical process to isolate the blue in Spirolina and take out the green to come up with brilliant blue dye. Stay tuned for my next cake utilizing these fabulous new dyes! I can't wait to try them.