In a bowl, combine flour, sugar, baking powder, and salt. Stir in blueberries and orange peel. In another bowl beat egg, add milk and oil. Stir into dry ingredients just until moistened. Pour into a greased 9X5X3 loaf pan. Bake at 350 degrees for 1 hour or until toothpick comes out clean. Cool in pan for 10 minutes, remove and cool on wire rack.