Too early or too late of melting will lead to the loss of air bubble
and a denser cake. Even though US-treated IES contributed to a significantly lower initial batter density
than non US-treated IES, it is possible that it was released at a too early
stage, before air bubbles began to expand. Therefore, without the protection from the lipid layer, air bubbles either collapsed or escaped
from the surface of the batter. This resulted in a similar cake density obtained
with US-treated and non US-treated IES.