I'm trying to make a simple white cake from a white cake mix but the cake keeps turning out more yellow than white. I need a bright white cake. I tried using shortening instead of oil but that didnt help and I am using only egg whtes. So I'm not sure why it I keep getting a light yellow colored cake? Any help would be great!!! thanks!

Did you add vanilla extract?

no vanilla added. I did add 7 up instead of water.

mmmm.....which cake mix are you using? maybe a different flavor would give what you are looking for.