Cake flour

Cake flour has the least amount of protein in it of all wheat flours. You want lower protein levels when making cakes and muffins so that they are more tender. Cake flour also differs from other flour because it is very slightly more acidic than other flours--this gives cakes a finer texture, and helps to keep things like nuts or chocolate chips from sinking because it causes the eggs in the batter to set more quickly. Pastry flour has a higher level of protein than cake flour, and does not have the acidity. If your recipe calls for cake flour, use cake flour. An acceptable alternative is to buy a southern grown all-purpose flour such as Red Band or White Lily, which have very low protein also, but are not as expensive as cake flour.