Liquid
Nitrogen IceCream
Introduction:
Nitrogen is safe to eat because it makes up ~75% of
our atmosphere. We breath it all the time. The liquid N2
used in this demonstration is much colder than home cooling
resources such as ice or snow, allowing the icecream to be
made very quickly. So quickly, in fact, that a "frozen pond" or "iceberg" effect
of a top frozen layer with a bottom solution layer will be
created. A quick discussion of why ice floats could be easily
woven in here, as well as the biological impact of lakes
and large ponds not freezing from the bottom up.
Materials:
- 4 cups of heavy whipping cream
- 4 cups of
skim milk
- 2 cups of sugar
- 2 tablespoons of vanilla
extract
- 4 liters of liquid nitrogen
Procedure:
Mix all the ingredients in a large stainless steel bowl with
a wooden spoon. Slowly pour the N2 into the bowl, continuously
stirring. The top layer will tend to "iceberg" and
will need to be broken down to allow the rest of the liquid
underneath to be vulnerable to the N2. A small cycle of
pouring the N2, breaking down the frozen layer, and adding
more N2 will result. When all the solution is semi-solid,
it is ready to serve.
Helpful Hints :
- Be sure to use a stainless steel bowl as
other types of bowls could shatter.
- Be sure to use a wooden
spoon as a plastic spoon will break and a metla spoon will
get QUITE cold.
- Make sure when handing out the icecream
that it isn't too cold; liquid N2 is -180o C.
- Small candy
(M&M's, crunched Butterfingers, etc.) can
add a lot of flavor. When in doubt, go long on the sugar
and vanilla. *grin*
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