SCIENCE: Keeping Whole-Wheat Flour Fresh

Have you ever wondered why pasta or baked goods made with whole-wheat flour can sometimes taste a bit bitter?

It helps to understand whole-wheat flour. Unlike refined white flour, which is derived from just the grain's stripped-down inner core, or endosperm, whole-wheat flour is made from the entire wheat berry: endosperm, germ, and bran. Because of this, it has a light brown color and a more pronounced wheat flavor.

Within a kernel of wheat, the endosperm contains nearly all the starch as well as the proteins (glutenin and gliadin) that combine when moisture is added to produce gluten, the protein that gives doughs their ability to stretch and rise. The germ is high in fat, active enzymes, non-gluten-producing proteins, and nutrients. The bran is the wheat berry's protective covering; it is mostly comprised of fiber and water.

The fat in the germ is the reason that whole-wheat flour has a shorter shelf life and a potentially bitter flavor: the unsaturated molecules of fat are easily oxidized and become rancid in a few months, especially if the flour is stored at room temperature.

For best results, use fresh flour from the market, store your whole-wheat flour in the freezer, or even grind your own flour yourself.