In the May 2005 issue of Discover Magazine, Joshua Foer wrote about attempts to increase popped popcorn’s volume, for instance by using vacuum cookers. Since popcorn is a product bought by weight but sold by volume, success means more profit.
Popcorn of today pops twice as big as the popcorn of 50 years ago and leaves 1/4 as many unpopped kernels (called, eek, “old maids”).
As a kernel heats up, the moister trapped inside its pericarp (tough outer shell) vaporizes and pressure increases. The starchy endosperm (stuff inside) melts. When the pressure gets high enough, the kernel explodes, “shattering its pericarp like a shrapnel grenade. The gelatinous starch instantaneously solidifies as it leaves its shell.”
The pericarp of popcorn transmits heat better than that of regular corn, and it’s four times stronger, so the pressure builds up and makes a more spectacular explosion. Brazilian scientists discovered that popcorn starch gets 60% puffier than regular corn endosperm.
Foer: “The corny taste has in fact been bred out of commercial popcorn intentionally, because it conflicts with the flavor of artificial additives and because it’s tough to grow big, high-yielding crops that are also tasty.”
Andrew Smith, author of Popped Culture: A Social History of Popcorn in America, says “I don’t think there’ve been improvements. There’ve been de-improvements. You should be able to taste a corny taste in popcorn. You could, thirty years ago. … If you seal your nose and put today’s popcorn in your mouth, it tastes like cardboard. … Americans don’t want popcorn. They want butter and salt.”
If you want to try the old-fashioned stuff you can order heirloom popcorn through Crown Jewel Gourmet.