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Re: [Phys-L] popcorn physics



On 2013, Jun 19, , at 09:37, Bill Nettles <bnettles@uu.edu> wrote:

-----Original Message-----
From: Phys-l [mailto:phys-l-bounces@phys-l.org] On Behalf Of Anthony
Lapinski

cut

I was just microwaving some popcorn -- one of my favorite snacks. I can
never get all the kernels to pop. Microwave the bag longer, and the popcorn
starts to burn. This has been a problem I've notices for decades.

I'm sure you realize that there are "hot spots" [but they move.] in the microwave oven. Also, outer "moisture" will shield the inner. And there is a statistical distribution of the moisture content of the kernals.

Most (all?) microwave popcorn bags have some solid fat (and think lots of hydrogen-like bonds) which I suspect is the main energy catcher. The oil gets hot and surrounds the kernels, acting as an efficient heat source for the kernel. As the melted fat is absorbed by the popped kernels, there are leftover kernels which don't get hot enough to pop, but the fat in the popped ones continues to absorb energy and reaches a temperature that scorches the white matter.

It would be an interesting experiment to put some popcorn in a bag with NO fat and see how much popping one gets. Looking at all hypotheses: 1) more popping, 2) less popping, 3) same popping, 4) no popping, and then a) even popping b) uneven popping.

I do know that you can pop popcorn using hot air without oil. I can't remember what happens if you try to pop with direct heat over a flame or in a dry pan. I think the popped kernels burn quickly in those "open flame" baskets.

I still have one for camping -- just hold it above at an appropriate height and shake vigorously. I've already posted my antique, (probably) cast iron popper, the dry pan with rotating agitator. Not incidentally this is the method of the 19th cent. bulk popper invention still in use in movie palaces.

------------------

I too quickly did the experiment and posted in "someone is wrong.


‎www.cleyet.org/Someone_is_Wrong/The%20fat%20is%20for%20palatibility%20only.pdf

bc, again a kitchen physicist, who eschews FAT.