The cake expansion increases with increasing temperature
of the batter according to the gas laws and with
increasing water vapor pressure from the liquid in
the mixture (Matz, 1992). As the ingredients play
an important functional role in the structure and
eating quality of the product (Conforti, 2006), cake
batters prepared from whole eggs containing egg
yolk lipids exhibit very fine bubbles in the crumb
(internal structure) of baked products leading to a
silky and tender texture. In addition, a formula
based on egg yolks containing added shortening
further changed the structural qualities of both the
batter and the baked cake (Matz, 1992). Baking
powder is also used in sponge cake and has been
suggested to be added at the final stage of
ingredient mixing (Matz, 1992).