Grease two 4.5 x 22 cm loaf pans. Sprinkle the yeast over the warm water. Let sit approximately 10 mins. until bubbling. In a mixing bowl, combine dry milk, sugar, buckwheat flour, bread flour, cinnamon, and salt. Add yeast mixture, and beat vigorously with hoock attachment or by hand for 8 to 10 mins. until the dough is silky and resilient, adding more flour as necessary to keep the dough from sticking. Place dough in a bowl greased with corn oil. Rotate the dough in the oil until it is well covered with oil. Cover with plastic wrap and let the dough rise in a warm place for 30 mins. or until it doubles in volume. Punch the dough down and let rise for another 30 mins. Divide the dough in half and form into logs. Place into the prepared loaf pans, bruch with whisked egg whites, and allow to rise further until bread reaches just over the lip of the pan (approximately 30 to 40 mins.) Make two diagonal cuts in the top of each loaf with a sharp knife and sprinkle lightly with 2 T. bread flour. Bake in a preheated 400 degree oven for 30 to 40 mins. or until crust is a dark golden bown and the bottom of the loaf is hollow sounding when tapped. Turn loaves onto rack to cool.