Potassium bromate (aka bromic acid or potassium salt) is a “maturing agent.” It comes in white crystals or powder.
It strengthens the gluten, makes the resulting dough easier to knead and better rising. It also causes the dough to be more elastic, particularly for commercial kneading machines. Some, though, feel that it makes the texture of the dough and the resulting bread too spongey.
When used in small amounts, it disappears during cooking. Traces of it remain only if too much was used, if the baked product hasn’t been cooked long enough, or if the baked product wasn’t cooked at a high enough temperature.
Other agents such as ascorbic acid, malted barley and monocalcium phosphate can be used as alternatives to provide the same enhancement effects.
Potassium bromate is seen as a carcinogen by some researchers, and has consquently been banned in several countries such as Canada, the UK and throughout the EU. Its use in flour is still legal in America and in Japan as of 2006. In America, Bromated Flour must have “bromated” somewhere on the label, and the quantity of potassium bromate in the flour cannot exceed 50 parts per million.