Combine first 5 ingredients in a large bowl, stirring well.
Whisk eggs with butter and orange zest in a separate large bowl. Stir in pineapple and bananas.
Add egg mixture to flour mixture, stirring until well blended.
Pour batter evenly into prepared cups.
Bake 20 minutes or until toothpick inserted in center of cupcakes comes out clean. Cool in pans 5 minutes, and then place on wire rack to cool completely.