Preheat oven to 350 degrees F.
In a large bowl, whisk together flour, sugar, baking powder, baking soda, & salt.
In separate bowl, mix together juice, egg, oil and zest, if using.
Add your wet ingredients to the dry, mixing just until dry ingredients are moistened.
Fold in the blueberries.
Divide batter into 3 mini loaf pans, or one large (9 inch) loaf pan (sprayed with non stick cooking spray, or greased with butter)
Bake for 30-35 minutes for mini loaves or approx. 55-60 minutes for large loaf, or until bread is golden and springs back when lightly pressed.
Allow to cool in pan for 5-10 minutes, then transfer to wire rack to finish cooling.
While slightly warm, pour glaze over top of bread loaves, if desired.