Preheat oven to 400 degrees F (200 degrees C).

Coat 12 standard-size muffin-pan cups with nonstick cooking spray.

In a large bowl, mix together all-purpose flour, whole wheat flour, dark brown sugar, baking powder, baking soda, cinnamon, and salt.

Create a well in the center of the dry ingredients.

In a separate small bowl, stir together buttermilk, applesauce, egg whites, and canola oil.

Pour the buttermilk mixture into the well of the dry ingredients.

Stir just until evenly moistened, being careful not to overmix.

Gently fold in the chopped apple and raisins.

Divide the batter evenly among the 12 muffin cups.

Bake in the preheated oven for 25 minutes, or until a wooden pick inserted into the center of a muffin comes out clean.

Turn the muffins out onto a wire rack to cool completely.