I remember studying in the Mishnah Berurah years ago about the possibility of making one’s own matzah using regular store-bought flour. If I recall correctly, the Chofetz Chaim brings this based on the ruling of the Mechaber in the Shulchan Aruch, that flour which has not come into contact with water may be used to make matzah.

However, modern flour production is quite different from what existed in the late 19th and early 20th centuries, and even earlier milling practices. Today many commercial flours have added ingredients such as vitamins, minerals, or other enrichment additives.

In theory, if someone needed to make their own matzah today using store-bought flour, what ingredients or production conditions would one need to check for on the flour label to ensure that it would still be acceptable—at least bedi’eved—for making matzah?