In a small bowl, stir together flour, baking powder, baking soda, and salt. In a medium bowl, beat margarine and sugar together. Add egg yolks and orange peel. Add flour mixture and orange juice alternately. In a small bowl beat egg whites until stiff. Fold egg whites and black walnuts into batter. Place in greased muffin tin filling 2/3 full. Bake at 350° for 15 minutes. Prepare glaze and spoon over muffins as soon as they come out of the oven.