Effect of Pre and Post-Harvest Treatments on Characteristics of ?Pawnee? Pecan Kernels



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The Hunter Lab color system and three visual rating scores (class 1 is the best) were used in this study to evaluate kernel color change and speckling, respectively, in ?Pawnee? pecan [Carya illinoinensis (Wangenh.) K. Koch] kernels. Three harvesting practices (?Direct?, early harvest and brought to the lab; ?Cluster?, late harvest; and ?Ground?, early harvest and kept on the ground of the orchard), four storage temperature combinations [oven at 80 ?C for 48 h then ambient temperature (?OA?), continuous ambient temperature (?AA?), ambient temperature then refrigeration at 6 ?C (?AR?), oven at 80 ?C for 48 h followed by refrigeration (?OR?)], and two shelling dates were conducted. Results indicated that ?Direct? and ?AR? treatments in the first shelling date were lighter and had more color saturation with less class 2 and 3 speckling. In contrast, 'Ground? and ?OA? treatments in the second shelling date were darker, and had less saturated color with a greater amount of dark spots. Another study was conducted to further understand the reasons of color changes and speckling appearance in ?Pawnee? kernels. Samples were subjected to four accelerating conditions (puncture, temperature, shelling, and storage time) assuming these might be positively correlated to reduced kernel color quality. The outcomes of this study implied that lightness, hue, and Chroma values were greater in 0 week of storage, shelled pecan, 25 ?C, not punctured kernel treatments and decreased in the three week, unshelled, and 40 ?C, punctured kernel treatments. Color changes were mostly related to the changes in lightness and hue, and to a lesser extent the changes in Chroma. Kernels from class 2 and class 3 of visual rating scale increased with an increase in the time of storage, accompanied with higher temperature. No significant effect was found for puncture or shelling treatments on speckling in ?Pawnee? pecan kernels.