During storage for 16 days at 0 or 4.5C or storage for 8 days at 20C, fresh raspberry (Rubus idaeus L. var. idaeus) fruit became darker, less red, and more blue as recorded in L* a* b* CIE coordinates. Cultivars maintained their relative at-harvest ratings throughout storage. Rates of change for cultivars during storage did not differ. Color changes depended on temperature, with rates of change fastest at 20C, especially during the first 4 days. Fruit stored 16 days at OC was more red and less blue than that stored at 4.5C. Maximum color change was reached after 8 days at 0 or 4.5C and after 4 days at 20C.
Jo Ann Robbins and Patrick P. Moore
Walter Boswell, Bernard Bible, and Suman Singha
Fruit of 34 peach (Prunus persica L. Batsch). cultivars were harvested at maturity and visually evaluated by panelists on a 1 to 10 scale, where 10 = excellent color. CIELAB coordinates (L* a* b*) of fruit color were measured at the midpoint between the stem and the calyx end with a Minolta CR-200b calorimeter on the blushed and ground areas of each fruit. Simple linear regressions of color coordinates with panel ratings indicated that blush chroma, blush L*, blush hue angle and E* (total color difference between ground and blush) all influence visual color evaluation. Not only does assessing fruit color with a calorimeter permit color to be reported in internationally accepted units, but the relationships indicate that instrumental values relate well to qualitative ratings.
Patrick J. Conner and Dan MacLean
Anthocyanin content and composition and CIE 1976 (L*, a*, b*) color space (CIELAB) color coordinates were examined for the skin of 22 muscadine grape (Vitis rotundifolia Michx.) cultivars and Muscadinia Planch germplasm. Analysis of berry skin extracts by high-performance liquid chromatography (HPLC) determined that anthocyanin content varied from less than 100 μg·g−1 in bronze and pink berries to over 5500 μg·g−1 in highly pigmented black berries. The anthocyanins delphinidin, cyanidin, petunidin, pelargonidin, peonidin, and malvidin were detected in their 3,5-diglucosidic forms. Analysis of berry color with a colorimeter revealed chroma (C*) ranged from 2.4 to 22.8 with the highest values occurring in bronze- and red-colored berries. As anthocyanin concentration increased, lightness (L*) decreased to a low of 20 to 23 in black-colored berries. Pink and red skin colors were primarily a result of lower levels of total anthocyanins, although there was also a shift away from delphinidin and petunidin production toward more cyanidin and peonidin. Malvidin, the most important anthocyanin for muscadine wine and juice color stability, was only abundant in a few clones, all of which had V. munsoniana (Simpson ex Munson) Small or V. popenoei (Fennell) Small in their pedigree. The interspecific hybrid ‘Fennell’s 3-way Hybrid’ had the largest proportion of malvidin, contributing ≈58% of the total anthocyanin content. This clone also had low levels of delphinidin and high total levels of anthocyanin, making it a promising source for the improvement of muscadine grape pigment profiles.
Jane E. Lancaster, Carolyn E. Lister, Peter F. Reay, and Christopher M. Triggs
The color of fruits and vegetables results from the presence of chlorophyll, carotenoid, and anthocyanin pigments. Instrumental measurements of color are used routinely in describing processes of changing color, such as fruit ripening. The applicability of using skin color measurements to predict changes in pigment composition was investigated using a wide range of fruit and vegetables. Skin color was measured using a Hunter Colorlab and represented as the coordinates X, Y, Z, L*, a*, b*, chroma (C*), and hue angle (ho). Identical skin samples were extracted and analyzed for chlorophyll, carotenoid, and anthocyanin concentration. Sets of pairwise scatter plots were generated for each set of color variables and for the chlorophyll, anthocyanin, and carotenoid pigments. There were linear relationships between ho and anthocyanin concentration and between L* and log [chlorophyll concentration]. Multiple regressions for each pigment variable and sets of color variables also were calculated. However, there was no unique linear combination of pigments that gave rise to a unique point in the color space. Conversely, a given set of coordinates in the color space can be accounted for by many combinations of pigments. Therefore, a given color measurement cannot be described in terms of a unique combination of pigments. Caution is urged in interpreting tristimulus color coordinates in terms of a simple change in pigment composition without prior knowledge of the pigment composition within the fruits and vegetables. The surface topography of fruits and vegetables may be of considerable significance in measuring color.
Alan W. Meerow and Tomás Ayala-Silva
uniform color space CIELAB derived from Gonnet (1993 , 1998) . Two color coordinates, a* and b*, as well as a psychometric index of lightness, L*, are defined. The L* is a measurement of luminosity, i.e., the equivalence of each color on the gray scale
Jaime Prohens, Adrián Rodríguez-Burruezo, María Dolores Raigón, and Fernando Nuez
color coordinates.” Fruit were cut transversally at the midpoint between the blossom and stem ends, and measurements were made in the central part immediately after being cut (0 min) and 10 min later. A well-sharpened knife with a straight edge was used
Ni Jia, Qing-Yan Shu, Dan-Hua Wang, Liang-Sheng Wang, Zheng-An Liu, Hong-Xu Ren, Yan-Jun Xu, Dai-Ke Tian, and Kenneth Michael Tilt
colors through value of L * , a * and b * . Within the CIELAB color coordinates, lightness (L * ) describes the lightness of the color, going from black (L * = 0) to perfect white (L * = 100); chromatic component a * takes a positive value for reddish
Alan W. Meerow
CR-400 colorimeter at CIE D65/2° illumination/viewer conditions. The color parameters correspond to the uniform color space CIELAB, derived from Gonnet (1993 , 1998 ). Two color coordinates, a* and b*, as well as a psychometric index of lightness, L
Craig A. Ledbetter and Mark S. Sisterson
, and kernel for each intact fruit; Calculation of hull percentage [(hull wt/fruit wt) × 100] and kernel percentage [(kernel wt/nut wt) × 100]; Measurements of kernel length, width, and thickness; and Measurement of pellicle color coordinates luminosity
Hsing-Ying Chung, Ming-Yih Chang, Chia-Chyi Wu, and Wei Fang
20 :B 80 treatment significantly increased the AC of red leaf lettuce. Table 4. Effects of different red–blue ratios [R 80 :B 20 , R 50 :B 50 , R 20 :B 80 , and cool white (CW)] on fresh weight (FW) of shoot, anthocyanin content, color coordinates