Preheat oven to 375°F. Line a 12-cup muffin tin with paper liners or coat with cooking spray.
Whisk whole-wheat flour, all-purpose flour, baking powder, baking soda and salt in a medium bowl until combined.
Whisk applesauce, yogurt, milk, lemon zest, lemon juice, eggs, vanilla and 7 tablespoons sugar in another medium bowl until combined. Add the flour mixture; whisk until just combined. Using a rubber spatula, gently fold in blueberries until evenly distributed.
Spoon the batter into the prepared muffin cups, about a scant ½ cup each. Sprinkle the tops evenly with the remaining 1 tablespoon sugar.
Bake until golden and a toothpick inserted in the center comes out clean, 22 to 26 minutes. Cool in the pan for 5 minutes; transfer to a wire rack. Serve warm or at room temperature.
