of each nut was selected for color measurement. Kernel color (L*, chroma, and hue angle) was recorded using a handheld spectrophotometer (CM-2600d; Konica Minolta Corp., Ramsey, NJ) with a 6-mm-diameter aperture and specular light was included. Two
Chen-Yi Hung, John R. Murray, Sarah M. Ohmann, and Cindy B.S. Tong
The color of red potato tubers is due to an accumulation of anthocyanins in periderm and peripheral cortex tissues. The objective of this study was to characterize changes in anthocyanin content and tuber surface color during tuber development. Using the red tuber-producing potato (Solanum tuberosum L.) cultivar Norland, we observed that chroma (intensity of redness) and anthocyanin content per unit of surface area of greenhouse-grown tubers decreased as tuber weight increased. There was no increase in hue (tint) during the same developmental periods. Using high-performance liquid chromatography (HPLC), we determined that pelargonidin and peonidin are the major anthocyanidins (aglycones of anthocyanins) in the tuber periderm. Northern blot analyses indicated that steady-state mRNA levels of dihydroflavonol reductase (DFR), an anthocyanin biosynthetic enzyme, continued throughout tuber development. These results suggest that anthocyanins are synthesized throughout tuber development, and that cell division and/or enlargement contribute to a decline in chroma and anthocyanin concentration.
Kenneth R. Tourjee, James Harding, and Thomas G. Byrne
Ligule color of a Gerbera jamesonii H. Bolus ex Hooker population was analyzed with a reflectance spectrophotometer having a spectral capability of 400 to 700 nm and a cv <3% for the variables hue, chroma, and value. The observations for each variable had a continuous distribution; these broad distributions are possibly bimodal. The repeatability of hue, chroma, and value, determined as the correlation between measurements made on plants in December and those made on the same plants the following April, are 0.83, 0.82, and 0.86, respectively. The phenotypic correlations between value and chroma, value and hue, and chroma and hue are -0.35, 0.73, and 0.11, respectively. Some possible biochemical implications concerning the interaction of anthocyanin and carotenoid pigments are discussed. Reflectance spectroscopy and Commission International de l'Eclairage 1976 (L* a* b*) color space notation provide an objective and precise method for incorporating color into a recurrent selection program.
L.J. Grauke, T.E. Thompson, E.F. Young Jr., and H.D. Petersen
The Munsell color system was used to study kernel color differences between four pecan [Carya illinoinensis (Wangenh.) K. Koch] cultivars (`Cheyenne', `Choctaw', `Western', and `Wichita') grown at four locations (Tulare, Calif., and Brownwood, Crystal City, and El Paso, Texas) during two seasons (1987 and 1988) and stored under different temperatures (20 to 24 °C and -5 °C). Kernel color changed over time from yellow to red hues and from lighter to darker values, but changed very 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 the most yellow of the cultivars tested and `Wichita' kernels were the 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 could not be distinguished 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 to 24 °C became darker and developed red coloration quicker than unshelled pecans. Variation in hue and value accounted for the majority of color difference between cultivars. Changes in hue accounted for the majority of color change over time. Differences among cultivars in value (lightness) were consistent over time.
Chae Shin Lim, Seong Mo Kang, Jeoung Lai Cho, Kenneth C. Gross, and Allan B. Woolf
– EL 0 )/(EL t – EL 0 )] × 100. Color change. Color changes of bell peppers were measured using a Minolta chroma meter (CR-200, light source D65; Osaka, Japan) calibrated with a white standard tile. Fruit skin color at the end of storage was
Todd W. Wert, Jeffrey G. Williamson, Jose X. Chaparro, E. Paul Miller, and Robert E. Rouse
harvest and at midharvest (greatest number of fruit removed per tree), a Konica Minolta CR-400/410 Chroma meter (Konica Minolta, Osaka, Japan) was used to test the chromicity values on the most and least blushed surface areas of five fruit from each 10
Christian Chervin, Peter Franz, and Fiona Birrell
Catherine Belisle, Uyen T.X. Phan, Koushik Adhikari, and Dario J. Chavez
(black) to 100 (white). Color space value a * ranges from positive (red) to negative (green) and b * ranges from positive (yellow) to negative (blue). Both a * and b * color values were used to calculate chroma = square root [( a *) 2 + ( b *) 2
Oscar Andrés Del Angel-Coronel, Juan Guillermo Cruz-Castillo, Javier De La Cruz-Medina, and Franco Famiani
lightness (L*), hue angle (h), and chroma (C*) values are reported according to MacGuire (1992) . The fruit weight loss during the postharvest period was determined by weighing the fruits daily and was expressed as a percentage of the initial weight at
Jessica D. Lubell and Mark H. Brand
period using a colorimeter (CR-400 Chroma Meter; Konica Minolta Sensing Americas, Ramsey, NJ) connected to a data processor (DP-400; Konica Minolta Sensing Americas). Commission Internationale de l’Eclairage (CIELAB, Vienna, Austria) measurements