Tuesday, March 3, 2015

Kernel color changes over time

   Most pecan lovers know that pecan kernels will turn reddish-brown if they are kept at room temperature for an extended period of time. The other day, we were discarding nut samples collected back in the fall of 2013 from our pecan breeding project. While most kernels had turned dark with age, I was surprised that one sample had retained a lighter color. In the photo above, I've placed kernels from this year's Kanza nuts next to one-year-old kernels harvested from three trees in our breeding plot. The straw-colored kernels of fresh Kanza nuts are the gold standard for fresh pecans. Without refrigeration, the majority of one-year-old kernels had turned dark and looked much the same as the kernels pictured above from trees KT214 and KT334. However, the kernels from tree KT342 stood apart from all other samples as having kernels that retained a fresh-looking appearance.

    With my curiosity peaked, I dug through our 2014 nut samples to find the sample from tree KT342 so I could compare it to the year-old nuts I already had in hand. The photo at left reveals that kernels from this tree do not change color even after a year in room temperature storage. Unfortunately, fungi had infested the 2013 kernels from tree KT342 so I wasn't able to perform a taste test to see if the the kernel had developed any rancidity in a year's time.
    Now we have another cultivar attribute to study in our breeding project--kernel color and shelf life. And for all those interested, KT342 resulted from a cross of Pawnee and Greenriver.