Manufacturers also fill shortenings with
preformed bubbles of nitrogen (around 10%
of the volume), and bubble-stabilizing
emulsifiers (up to 3% of the shortening
weight). Butter is best aerated at a relatively
cool 65ºF/18ºC, while shortening creams most
effectively at a warm room temperature,
between 75 and 80ºF/24–27ºC.
Fat Replacers The moistening and tenderizing
effects of fat — but not its aerating abilities
— can be imitated by some concentrated fruit
purees, notably prune, apple, apricot, and
pear. Their high levels of viscous plant
carbohydrates, mainly pectins and
hemicelluloses, bind water and also interrupt
the gluten and starch networks. So these fruit
purees can be used to replace some of the fat
in cake recipes. The result is usually moist
and tender, but also denser than a full-fat
cake.
Techniques for Aerating Cakes