A kernel of wheat, Triticum aestivum, is about 92 percent endosperm and about 2 or 3 percent germ (the germ contains the embryo, the microscopic new wheat plant that would grow from the planted kernel). The remaining 5 percent of the kernel’s bulk is a thin protective sheath called the bran. The bran contains some iron but is indigestible. The nutritious germ contains an oil that can turn flour rancid if it isn’t removed in milling.
What's Good About White Flour
The fact that white flour lacks bran and germ allows a loaf of white bread to bake up light-textured, tall and soft. While kneading and baking dough, you want to develop the strands of gluten in the flour that stretch and raise the loaf by holding in the bubbles of carbon dioxide that yeast creates. Bran cuts through gluten strands, releasing some carbon dioxide from the dough and making the loaf dense and chewy. Wheat germ oil softens gluten structure, which also inhibits the formation of a tall, strong loaf.
What About Bleaching?
All wheat flours need to age to make good bread. During natural aging, a bin of flour is exposed to light and oxygen, which changes flour’s color from yellow to ivory or white. It also chemically alters the flour so that it will develop a better gluten structure than it would have if it had not been aged. Unaged or young flours used to be called “bucky,” and they made coarse, unappetizing loaves. Today, unbleached flours can have their aging process assisted by exposure to potassium bromate, which is still legal in the U.S., even though European countries have banned it as a carcinogen. Bleached flours are treated with benzoyl peroxide to give them the white color that consumers expect.
All-purpose white flour has a protein content of about 10 percent, compared to about 13 percent for whole-wheat flours. The B vitamins and iron lost in the removal of bran and germ are replaced after milling, creating enriched flour.
The Uses of White Bread
White bread’s gentle taste and firm structure make it excellent for sandwiches, whether the filling is something strong like ham or more delicate like a cream cheese and fruit combination. Leftover white breads make the best base for savory croutons, bread stuffings or sweet French toast recipes. Good homemade white breads also dissolve best in bread soups, thickening the broth without turning it gritty or gummy. White bread can accompany all meals because it complements the taste or texture of anything it is served with.