Thoroughly combine flour mix with salt, baking powder, and xanthan gum.
Beat egg whites until stiff, set aside.
Cream sugar, zest and butter, add egg yolks and mix well.
Add a bit of flour, then some orange juice to egg mixture, mix well then alternate adding the four and juice until all is combined. Fold in cranberries, egg whites.
Pour into a greased loaf pan and bake at 375°F for 50 minutes, or until internal temperature of loaf reaches 205°F, using an instant read thermometer.