In large bowl, dissolve yeast in warm water. Add sugar, oil, salt and 4 cups of flour; beat until smooth. Add enough remaining flour to form a soft dough. Turn onto a floured board; knead until smooth and elastic, about 6 to 8 minutes. Place in a greased bowl, turning once to grease top. Cover and let rise in a warm place until doubled, about an hour. Punch dough down, then divide in half. Roll each half into a 15 x 10-inch rectangle. Roll up from long side and seal well. Place with seam side down on a greased baking sheet sprinkled with cornmeal. Beat egg white and water; brush over loaves. Sprinkle with sesame seed. Cover with plastic wrap sprayed with nonstick cooking spray. Let rise 30 minutes. With a knife, make 4 diagonal slits across top of each loaf. Bake at 400° for 25 minutes.