Preheat oven 350ºF. Spray two 8-inch pans with vegetable pan spray.
In large bowl, combine cake mix, juice, egg whites, oil and zest; beat with electric mixer on low until combined. Beat mixture on medium speed 2 minutes. Divide batter into the two pans.
Refer to baking chart in techniques section for baking times and temperatures for specific pans.
Cool 10 minutes in pan on rack; remove and cool completely before decorating.
Makes about 5-1/2 cups batter.