In a large mixing bowl stir together the flour, baking powder, baking soda salt and cinnamon. In a medium bowl stir together the egg whites, zucchini, sugar, cooking oil and lemon peel. Add to the flour mixture, stirring just till combined. Stir in the walnuts. Pour the batter into a nonstick 8x4x2 loaf pan.
Bake in a 350oF oven about 50 minutes or till a wooden toothpick inserted near the center comes out clean.
Cool the bread in the pan on a wire rack for 10 minutes. Remove the bread from the pan and cool completely on the rack.
From the Dinner Co-op