too bad blueberry isnt blue... most of the blueberry strains i have had has all been similar... very fruity, bright green, bright orange pistils( best point of harvest 4 blueberry), There was one time where a certain strain had a blue "tint" to it... however it wasnt near as potent as my other encounters... purple however.. i have seen some crazy purps and all with varying potency....
For food coloring i dont know too much about it.. but i would thinkg it would produce a harsher smoke. I know it is oderless and tastless but im not too sure how oderless and tastless the smoke will be. I mean food coloring isnt meant to be smoked. I dont even know what food coloring is made up of... is it some kind of HCL or salt???
As far as just physical changes i would think a strong color would have to be used.... i wonder what would happen if you used some green food coloring... i would hope for some type of neon kryptonite looking shit...
just my 2 cents...maybe a lil more