Stir together 2 cups flour, cornmeal, dry milk, oat bran, yeast, salt and sugar in a large bowl. Heat water, oil and honey in a small saucepan over medium heat until very warm, about 8 minutes. Add the warm liquid and whole egg to the flour mixture and blend with a mixer set at low speed or by hand until well combined. Gradually stir in remaining 3½ cups flour until the dough pulls away from the bowl.
Turn out onto a lightly floured board and knead until dough is smooth and elastic, about 10 minutes, adding additional flour as needed to prevent the dough from sticking. Place dough in a bowl, cover and let rise in a warm, draft-free place for about 1¼ hours.
Punch the dough down, and divide it in half and shape each portion into a ball. Return the dough to the bowl, and let rest for 15 minutes, covered. Lightly oil two 8-by-4-inch loaf pans and sprinkle with cornmeal. Shape balls into loaves to fit pans, cover and let rise for about 1 hour.
Preheat oven to 350°F.
Uncover the dough and brush the tops of the loaves lightly with beaten egg white. Sprinkle with sesame (or poppy) seeds. Bake the loaves until the tops are golden brown and the bottoms sound hollow when tapped, 30 to 40 minutes. Remove from the pans and let cool on a wire rack.