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United States Department of Agriculture

Agricultural Research Service

Title: The Effect of Year, Cultivar, Location and Storage Regime on Pecan Kernal Color

Authors
item Grauke, Larry
item Thompson, Tommy
item Young, E - RETIRED
item Petersen, H

Submitted to: Journal of American Society of Horticulture Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 17, 1997
Publication Date: N/A

Interpretive Summary: We used the Munsell Color System to rate the color of pecan kernels collected from 4 cultivars grown at 4 locations over two years, and stored under different conditions. This visual system of color rating recognizes three attributes of color: hue (spectral region, e.g., red, orange, yellow, green, blue, or violet); value (lightness, from black to white); and chroma (color saturation, from neutral gray to pure color). We found that differences between years, cultivars, locations, and storage conditions all influence patterns of pecan kernel color expression. Kernel color differences between pecan cultivars were due to variation in both hue and value. Some cultivars, such as 'Cheyenne,' had kernels that were more yellow and lighter than others, while cultivars like 'Wichita' had kernels that were more reddish than others. All kernels became more reddish over time in storage, but 'Wichita' kernels showed the greatest change. Kernels sstored unshelled maintained color better than those stored shelled. Froze kernels were more reddish than fresh kernels.

Technical Abstract: Munsell Color System was used to study kernel color differences between 4 pecan cultivars (Cheyenne, Choctaw, Western, Wichita) grown at 4 locations (Tulare, CA; and Brownwood, Crystal City, El Paso, TX) during two seasons (1987, 1988) and stored under different temperatures (20-24C & -5C). Kernel color changed over time from yellow to red hues and from lighter to darker values but changed little in chroma. Initial ratings of each color attribute by cultivar were positively correlated with patterns of change in that attribute over time. Kernels collected in 1987 were more yellow and had greater color saturation than kernels collected in 1988. Cheyenne kernels were most yellow of any cultivar tested and Wichita kernels were most red. Cheyenne kernels were lighter than those of any other cultivar. Kernels frozen 6 or 12 months were more red in hue than unfrozen kernels but not distinguishable on the basis of value (lightness). Kernels frozen 12 months had reduced chroma compared to those frozen 6 months or unfrozen Shelled kernels of 'Wichita' changed hue more in storage than kernels of other cultivars. Shelled kernels held at 20-24C became darker and red colored more quickly than unshelled pecans. Variation in hue and value accounts for the majority of color difference between cultivars. Changes in hue account for the majority of color change over time. Differences between cultivars in value (lightness) were very consistent over time.

Last Modified: 7/23/2014
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