Always buy unbleached flour. Bleached flour is just that, it's been bleached to be white and it's cheaper. Flour turns white with age but most companies don't want to hold the flour that long because it cost more to store it so will use the bleach method. The short cuts of the big food companies will (and probably have) make you sick. People keep paying for slop and it's money in the pockets of those that won't eat their own product.