Preheat oven to 350°F. Grease and flour a 12-cup Bundt pan.

Beat egg whites with an electric mixer until soft peaks form. Add 1/4 cup sugar and beat until stiff peaks form. Set aside.

In a different bowl, cream butter and remaining sugar until fluffy, about 3 minutes. Beat in eggs, one at a time, sour cream, vanilla and orange oil.

Stir together flour, baking powder, baking soda and salt in a medium bowl. Add to batter alternating with lemon and orange juices. Fold in whites. Pour into prepared pan.

Bake cake for 45 to 50 minutes, until a knife inserted in the center of the cake comes out clean. Cool 15 minutes. Remove from pan to wire rack. Cool completely. Sprinkle with powdered sugar.