It is well known that color differences between objects
vary depending upon the color region (e.g., red region
vs. green region) and are not necessarily linearly correlated to visual color differences (Hunter and Harold
1987). Therefore, color difference (ΔE*ab) was calculated using the CIE 1976 L*a*b* formula (Hunter and
Harold 1987; Konica Minolta 2007) to give a single
value that indicates relative differences in color. The
higher the ΔE*ab value, the greater the difference in
color between two objects. It should be noted that the
ΔE*ab threshold value at which the human eye can
distinguish a difference is unknown and varies depending
on the color. For simplicity, we only further evaluated
color of treated tubers that had ΔE*ab values greater
than 1.0 (values highlighted in bold in Table 4) com-
pared to the corresponding control tubers.
For the at-harvest samples the color difference values
were calculated as follows: