. A standard white tile (X = 87.01, Y = 0.3185, Z =
0.3365) was used to calibrate the instrument and L*, a* and b* values
were directly taken from the colorimeter. The Hue value (a/b) and the
overall colour change (ΔE = √ΔL2 + Δa2 + Δb2
) were calculated
based on measured L*, a* and b* values