Why popcorn pops? (The Popcorn Board 2011)
The three main elements as to why pop corn
pops are:
1.
The percentage water content
within the popcorn seed.
2.
How hard the shell of the
popcorn is, and how in tacked the shell is.
3.
How starchy the centre of the
popcorn is.
Popcorn is a type of maize, which is part
of the grass family. There are three parts to the popcorn seed.
1.
The germ
2.
The endosperm
3.
The pericarp
Available
at: http://analytical.wikia.com/wiki/Endosperm(Accessed:
6th march 2013)
The most
important part of the popcorn is the pericarp. The pericarp is the perfect
thickness so that it protects the germ and the endosperm from damage but is
also the perfect thickness so that it can burst open.
Popcorn
contains a small amount of water. The overall water percentage of the whole
seed needs to be just below 14% for the seed to be able to pop. This is because
the water needs to be heated up within the seed to ‘pop’ the popcorn. When the
water reaches 212°C the water turns to steam. This would normally happen at
100°C but because of the pressure within the seed, the temperature has to be
higher to boil the water. The pressure inside the popcorn reaches 135 pounds
per square inch (what makes popcorn pop 2012) after the water has boiled. The starch within the centre of the of the
popcorn starts to expand and cause the foam to form in airy bubbles. The
bubbles solidify together and rapidly cool off (Daven Hiskey 2010)
D, Hiskey. (2010) Why popcorn pops. Available at:
http://www.todayifoundout.com/index.php/2010/07/why-popcorn-
pops/ (Accessed: 10 February 2013)
What
makes popcorn pop (2011) Available at:
http://www.popcorn.org/ForTeachers/TeachingGuide/WhatMakesPopcornPop/tabid/88/Default.aspx
(Accessed: 9 February 2013
The Popcorn Board (2011) Why popcorn pops. Availible at: http://www.popcorn.org/ForTeachers/TeachingGuide/WhatMakesPopcornPop/tabid/88/Default.aspx
(Accessed: 9th February 2013)
I think popcorn is a great piece of "magical" science at the campfire - especially if I take some scales so I can measure weight of popcorn before and after heating. From your explanation above, I think you should speculate on the difference in weight that we would find.
ReplyDeleteI will bring marshmallows next time - how about doing a piece on the science that explains the change in marshmallows when they are toasted on the fire? (Try it at home beforehand if you want, and bring your explanation to the woods???)
But hey, everyone does marshmallows and lots do popcorn, coffeemate and smores. What else could we do with food on the fire to get people thinking about the science of changes in materials???