In addition, engineering fracture mechanics suggest that
pressure vessels fail at the weakest point in the structure
and critical pressures for particle fragmentation
depend on surface area to volume ratio Thus less spherical kernels may have a predominant
failure point in the pericarp through which molten starch of
popcorn endosperm tends to expand and create flake morphology
with appendages in only one direction, whereas more spherical
kernels tend to have an increased number of fragmentation points,
allowing the endosperm to expand and form appendages in
multiple directions.