Heat the oven to 425 F. Line a 12-cup muffin pan with paper or foil liners.
In a large bowl, combine flour, cornmeal, brown sugar, baking powder and salt. Stir to blend evenly.
In a separate bowl, combine milk and egg whites. Add chopped apple and corn kernels. Whisk to mix evenly, and pour over the flour mixture. Stir gently until the dry ingredients are slightly moist. The batter will be lumpy.
Fill prepared muffin cups 2/3 full and bake about 30 minutes. Tops of muffins should spring back to the touch when they're baked.