Thursday, October 20, 2016

Pecan maturation after shuck split

   The date a pecan cultivar splits its shuck is an important indicator of how well that cultivar is adapted to the climate at a particular location. However, pecan maturation does not stop at shuck split. A pecan does not become fully mature and achieve full flavor until the kernel dries down to under 12% moisture. To demonstrate how pecan kernels change as they dry, I harvested some Stuart and Kanza nuts (photo above). The Stuart nuts were loose in the shuck but the shuck had yet to split open. The nuts inside the Stuart shucks are still at their maximum moisture content. Kanza nuts split shuck 3 weeks ago and the nuts inside have begun to dry down.

    When I cracked open both cultivars I had lots of trouble producing full kernel halves (photo at right). Both kernels were tight against the shell so that when I  cracked the shell  I also broke the kernel. In handling both kernels, I could feel the moisture on my fingertips. The Stuart kernel was really wet, giving the kernel a sticky and rubbery feel. In contrast, the Kanza kernel was smooth but still slightly rubbery.
   The obvious difference between these two cultivars was kernel color and appearance. The high moisture Stuart nut was white and covered in brown fuzz. The shell packing material in the dorsal groves was a sticky mess. The Kanza kernel appeared to have normal color and the packing material fell free of the kernel.
    Looking at these two pecan cultivars gives us a pretty good idea of how pecan kernels mature after shuck-split. The drying process helps the kernel separate from the shell and all internal packing material. The outside of the kernel dries to a golden brown color. Full pecan flavor is achieved only when kernels dry down to less than 12% moisture.