ICE,Cream...
Chemistry
and
By Brian Rohrig
istock.com, photos.com, shutterstock
Air is important!
If you have ever made ice cream, you
already know what goes into it, ingredients
such as milk, cream, and sugar. But there is
one main ingredient that you may not have
thought about, probably because you can’t see
it—air.
Why is air so important? If you have ever
had a bowl of ice cream melt, and then refroze
it and tried to eat it later, it probably did not
taste very good. If you set a whole container of
ice cream on the table and let it melt, the volume of the ice cream would simply go down.
Air makes up between 30% and 50% of the
total volume of ice cream.
6 Chemmatters | February/march 2014
brands. One side effect of adding
To get an idea
a lot of air to ice cream is that it
of the effect of
tends to melt more quickly than
air on ice cream,
ice cream with less air.
think of whipped
The amount of air also has a
cream. If you whip
huge effect on the density of
air into cream, you get
the ice cream. A gallon (3.8
whipped cream. Whipped
liters) of ice cream must weigh
cream has a different texture
at least 4.5 pounds, making
and taste than plain cream. Plain cream
the minimum density 0.54
tastes sweeter than whipped cream. Just
gram per milliliter (or 540
like ice cream without air, pure cream has a
grams per liter). Better brands
sickly, overly sweet taste. This is because the
have higher densities—up to 0.9
structure of a substance can have a big effect
grams per milliliter. The next
on how it tastes. The structure often controls
time you visit a grocery store,
the rate at which flavor molecules are released
compare cheaper and more
into the mouth. The larger the structure (of
expensive brands by holding
ice cream, in this case), the longer it takes
a container in each hand—you
for flavor molecules to be released. Flavor
should be able to notice a differmolecules trigger receptors on the mouth and...