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Ice cream:
A Public Radio Commentary
by Bill Hammack
Listen using RealAudio
Recently I tossed out my ice cream maker. I've tried for years to
make great ice cream; but it was never as good as what I could
buy. So, I took a look at how ice cream is manufactured. I
learned it's a very tricky business.
To the food engineer it's just air bubbles, oil globs and ice
crystals suspended in water, but the key to engineering ice cream
is getting all these bubbles, globs and crystals to be the right
size. The oil comes from milk fat, which, of course, doesn't mix
readily with the water. So the first step is a device that
shatters the fat globules so they'll mix with the water,
otherwise the cream will float to the top. Next, air is pumped
in.
Ice cream can be up to fifty percent by weight air, although by
law a half gallon must weight at least two pounds, two ounces.
Adding in the right amount of air can make the difference between
mediocre and excellent ice cream.
Too much air insulates the ice cream, making it melt slowly in
our mouths and ruining its flavor. As it melts the chemicals
containing the flavor are actually boiled on our tongues. The
tropical orchard vanilla, for example, contains dozens of
flavors. Each has a different boiling point that makes the
vanilla play out in a certain time sequence on our taste buds.
The more air then, the slower the melting and the less rich the
flavor.
So, when you're in the supermarket checking out ice cream what
should you look for? Find the highest density ice cream; that is,
the heaviest half gallon. Most ice creams weigh close to the
legal limit of two pounds, but premium brands can be nearly twice
as heavy.
After you buy it I suggest you rush home. It is imperative to
keep the ice cream at a constant temperature, otherwise it loses
texture. If the ice crystals are bigger than one-thousandth of an
inch, the touch receptors in the roofs of our mouths detect them.
So, when you get that ice cream home, toss it in the freezer, and
keep it closed. Opening the door makes the freezer heat up only
slightly, but enough to melt the ice crystals. Then when the door
is closed the water freezes, but this time freezing into larger
crystals that make the ice cream crunchy.
One more ice cream tip for you: If you want excellent ice cream,
go to New Zealand. They rank number one, per capita, in ice cream
consumption. Each person eats about seven gallons a year. Their
snow-fed rivers, clean air, sunshine and year-round grazing on
rolling pastures lets their cows make milk that produces some of
the best ice cream you'll ever taste.
Copyright 2003 William S. Hammack Enterprises
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