Dissolve yeast and 1 teaspoon sugar in water, stirring well; let stand 5 minutes.
Combine yeast, remaining sugar, milk, oil, baking powder, and salt in a large mixing bowl; mix well. Stir in 2 cups flour. Cover; let rise in a warm place (85°), free from drafts, 1 hour or until doubled in bulk.
Stir dough mixture; add enough remaining flour to make a stiff dough. Turn dough out onto a heavily floured surface; knead 8 minutes or until smooth and elastic.
Place in a large, well-greased bowl, turning to grease top. Cover and refrigerate overnight.
Divide dough into three equal portions; shape each into a loaf. Place in 3 greased 9- x 5- x 3- inch loaf pans. Cover and repeat rising procedure 1 1/2 hours or until doubled in bulk.
Bake at 350° for 50 minutes or until loaves sound hollow when tapped. Remove bread from pans immediately; cool on wire racks. Slice and serve.
Note: All or portions of the dough may be kept covered and refrigerated 4 to 5 days.