*2.3. Color Measurements*

The color of each specimen was measured using a spectrophotometer (model UV-2600; Shimadzu, Kyoto, Japan) with an integrated sphere (model ISR-2600 Plus; Shimadzu). Diffuse reflectance measurements were performed in the range of 350–800 nm in 1-nm steps. Color was measured according to the Commission International de L'Eclairage (CIE) *L\*a\*b\** color system [29] (*n* = 5), which has a lightness scale, *L\**, and two opponent color axes, *a*\* and *b*\*. The redness and greenness are represented by the *a\** values and the yellowness and blueness are represented by the *b\** values.
