Preheat the oven to 350 F. Line a muffin pan with paper or foil liners.
In a large mixing bowl, combine the flours, sugar, baking powder, baking soda and salt. Stir to mix evenly.
In a separate bowl, add the egg whites, canola oil, applesauce, orange peel and orange juice. Using an electric mixer, beat until smooth. Add to the flour mixture and blend just until moistened but still lumpy. Stir in the chopped rhubarb.
Spoon the batter into 12 muffin cups, filling each cup about 2/3 full. Sprinkle 1/2 teaspoon of chopped pecans onto each muffin and bake until springy to the touch, about 25 to 30 minutes. Let cool for 5 minutes, then transfer the muffins to a wire rack to cool completely.