A mean rating of pink coloration was calculated by the
following formula: N½ -
ð Þþ 0x0 ð Þþ N1x1 ð Þþ N2x2 ð Þ N3x3
Ntotal; where Ni = number of tubers in each rating
category.
Ten tubers 57 to 113 g in size also were collected during
grading, thoroughly washed in tap water, then air-dried for
24 h prior to surface color measurements at harvest. The
HunterLab CT1100 ColorQuest Colorimeter (Hunter Associate Laboratories, Inc., Reston, VA) was used to measure
L*, a* value, b* value, chroma (C*; saturation/color intensity), and hue angle (h°; color itself) at two random locations
on each tuber. Measurements were performed under total
reflectance mode, illuminant D65, 10° observer angle, and
2.54 cm port diameter. These 20 measurements per sample
(10 tubers × 2 locations) were averaged to get one mean
value.