Although most health-conscious home cooks might prefer to substitute whole wheat flour for all of the white flour in yeast and quick bread recipes, a 100% whole wheat product will yield disappointing results.
Yeast and quick breads rely on gluten for their rise, texture and structure. Whole wheat flour does not develop gluten as well as white flour because it contains fewer gluten-forming proteins…plus, the bran in whole wheat flour can cut the delicate strands of gluten during kneading or mixing.
So breads made only with whole wheat flour generally do not rise as high and are heavier and denser in texture.
If you are converting some of your own recipes, start by substituting 25-50% whole wheat flour for the white flour.
If the recipe is for a yeast bread that uses all-purpose flour, try using a combination of whole wheat and bread flour. The bread flour will provide more gluten than the all-purpose flour, making up for some of the gluten lost to the whole wheat flour.
In quick breads, substituting 25-50% whole wheat flour for white flour generally will also get you the best results.
Some cooks report greater success by replacing more of the white flour with whole wheat pastry flour, a lower protein, finely ground product that is available at specialty grocery and health food stores. This substitution often requires changes in liquid measurements due to the lower water-holding capacity of pastry flour.