that's just how they are man, unfortunately a clean white led does luminate blue streams of light, don't ask me for the technical term but I learnt that one when LED'ing out my lexus aircon and dash panels.
Best bet is to get as high MCD LED's as you can get, then depending on where your placing them and the effect your trying to get.
e.g. if you want to make it have a direct point/dot to focus the light on then leave as is
but if you wanna make a glow effect where the light is evenly dispersed you get a fine sander and sand teh round head down, that way when installed it will disperse the light more cleanly giving a 'glow' effect.