好像有三种东西ZT

Most flour companies add benzoyl peroxide or chlorine dioxide to chemically whiten -- that is, bleach -- their flours. Some add potassium bromate to artificially strengthen their flours. When you hear benzoyl peroxide, you probably think acne cream, in which benzoyl peroxide is the active ingredient. Chlorine dioxide? Anyone who's done the laundry or cleaned the swimming pool knows that chlorine is the key agent in liquid bleach. For its part, potassium bromate is a suspected carcinogen that has been banned from food products in Europe, Japan, and Canada. Food in California that contains potassium bromate must bear a warning label.