🚀 go-pugleaf

In article <m0mPFSn-000FNAC@wet.uucp>, wet!noah@well.sf.ca.us (Noah
Spurrier) writes:

|>Anyone out there interested in some amateur physics and chem of pop corn?
|>
|>I am looking for any information or references to the physics and chemistry
|>of pop corn.  What is the velocity of the pop (i.e. How long does it take
|>to go from kernel to pop corn?)  What is the mechanism of the pop?  What
|>temperatures and pressures are formed inside the corn kernel in order for
|>it to pop?  Why does the material inside the kernel behave the way it does?
|>Do any other grains behave this way?  Do we get Rice puffs the same way we
|>get poped corn?

Well, if I could find my 10th grade science fair project, I could send
you a pretty good summary.  It concerned the use of a vacuum to
enhance the popping of corn.

Here's what I remember:

Corn pops because heat converts internal water into steam, which at
around 400 F explosively breaks the kernel's shell and expands.  The
shell must be pretty hard, since there was no appreciable difference
in popping temperature in a vacuum.  Rice and wheat pop in about the
same way, although they lack the hard shell that makes popcorn "pop"
-- they tend to puff instead, but in both cases it's due to expansion
of steam.

You could probably figure out the vapor pressure of water at 400 F to
get a good estimate of the maximum internal pressure in the corn
before it pops.  

Professor C. Gene Haugh of Purdue University graciously answered a
number of questions for me fifteen years ago; I have no idea whether
he is still there.  I still have my autographed "Orville Redenbacker"
popcorn cookbook, though.  There's an American Popcorn Institute
somewhere; you might check on the back of popcorn containers or call
one of the big packers.

The folks that worry about these things are called "agricultural
engineers," not materials engineers, but I thought I'd answer this one
since it was the start of my scientific misadventures.

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Ken Meltsner                        | meltsner@crd.ge.com (518) 387-6391
GE Research and Development Center  | Fax:  (518) 387-7495
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