I think that if you put it in your flour that it will oxidize a lot of stuff and not necessarily be that effective. Most people do not have problems with the microbes found in flour unless they have a peculiar sensitivity or their bodies are quite run down. I would assume that baking will kill much of the microbes that might be there. This is why when you bake bread or something, when it starts to mold or rot it starts on the outside, where it is exposed to new invading microbes, not in the middle of the loaf where high heat had killed most everything
If flour were such a big issue for me I just wouldn't eat it.
"The nurse should be cheerful, orderly, punctual, patient, full of faith, - receptive to Truth and Love" Mary Baker Eddy