Popcorn kernels

​Waxy and amylose corns are specialty corns influenced mostly by single gene mutations.  Popcorn genetics are more complicated, perhaps the consequence of a number of genetic changes that occurred in the early days of corn development in Mexico.  There is evidence that it was used by people in Mexico at least 5500 years ago. A major kernel structural factor causing popping is the ‘flint’ character of a hard pericarp, that is impervious to moisture passage.  Consequently, heating the kernel results in internal steam pressure. As the temperature increases the internal soft starch and protein resulting in a gelatin-like substance.  When the pressure finally breaks through the pericarp, the gelatin expands into a foam.

Pericarp thickness and endosperm starch type are two major characters affecting the successful popping.  Both characters are known to be affected by several genes, some major and some minor.  Other characteristics such as the size of the ‘pop’ are also genetically linked.  There are studies that have associated popping characteristics affected by at least minor genes on each of the 10 chromosomes of corn.
 
Those folks several thousand years ago didn’t need to know about molecular biology to understand the fun of eating popcorn and we really, really appreciate their persistence in passing along this feature of corn.