2.2 Pericarp browning assessment and color changes
Browning was assessed visually by measuring the
total browning areas of the pericarp on each of the twenty
fruits. The following scale was used: 1 = no browning
(excellent quality), 2 = slightly browning, 3 = browning on
less than 25% of the total surface, 4 = 25-50% browning,
and 5 > 50% browning (poor quality) (Jiang and Li, 2001).
A browning index was calculated using the following
formula, Σ(browning scale × percentage of fruit in each
class). Fruits having a browning index above 3.0 were rated
as unacceptable. The color of the outer pericarp of longan
was measured with a colorimeter (Color Quest XE) according
to the CIELAB scale. The degree of browning was
expressed as L*, Chroma (C* = [a*2 + b*2]1/2) and hue angle
(hº = tan-1 b*/a*) values. The results were expressed as a
mean value from four replications of 20 measured samples.