In large bowl mix flours, baking powder, baking soda, cinnamon, nutmeg and salt. Stir to mix well.
In mixing bowl beat sugar and oil until combined. Add egg, egg whites and vanilla and beat 1 minute. (Save remaining yolks for another use.) Beat in apple juice.
Add flour mixture, using low speed just until mixed. Stir in apple slices and walnuts. Pour into generously greased and floured 10-inch tube pan or 12-cup bundt pan. Smooth surface and place in center rack of oven. Bake at 350F 45 to 50 minutes, or until wood pick comes out clean. Cool 10 minutes on rack and gently remove from pan. Dust with powdered sugar, pressed through fine sieve. Serve warm.
