An excess acidifier is also added, however it isn’t used in combination with the sodium bicarbonate. Instead it lowers the batter pH to facilitate the starch gelatinization and maintain the egg white protein foam volume in the baking cake. At a lower pH, the egg white proteins are able to entrap more air during both preparation and baking. The optimal pH for the batter is between 5.5 and 6.8. It also helps to create a whiter cake, which is more desirable to consumers. It is typical that the excess acidifier is the same as that used to react with the balanced chemical leavener.