Annatto has a distinctive taste as well. I can taste it, anyway. I've made many attempts to extract it from the seeds, so I'm a little sensitive to the flavor.
Natural red color is easy to get from beets. Cut them and leave in a bowl of water. Red will bleed quickly.
I haven't use hibiscus flowers, but they give a red coloring that I think would work great. Magic Hat uses it to make a beer, Wacko, which is red.
