3.3. Observed Variables
3.3.1 Physical Attributes
3.3.1.1. Fruit Resistance kgfcm
2
Mangosteen fruit was pressed until breakdown to see the level of easiness for fruit to be opened by using fruit resistance tool. The observation was done
every two days with 16 times of observation, each of which two fruits were used.
3.3.1.2. Pericarp Water Content
Pericarp sample g were weighed, and placed in the paper envelope. The sample was dried in oven at 105
o
C for 96 hours, then cooled down in desiccators and weighed. PWC was calculated using formula:
Pericarp water content =
a −b
a
× 100, where a = Fresh weight g b = dried constant weight g
3.3.1.3. Weight Loss
Loss of fruit weight is measured based on the percentage of the reduction in the weight since the beginning up to the end of the storage period. The weight loss
was calculated using the following formula: Weight loss =
W −Wi
W
× 100, where W = Weight at initial storage g Wi = Weight at i
th
observation g
3.3.1.4. Fruit and Sepal Color
The observation of fruit and sepal color was conducted every two days to see colour development during storage. Fruit and sepal color was measured using
Color Reader CR-10 that was already calibrated. The tool consists of color notation color system L, a, and b. Color system L means the brightness with
value 0 black until 100 white. The color system a and b is chromaticity coordinate. It means that chromatic mixture of red and green with value +a from 0
to +60 for red and –a from 0 to -60 for green color. b value means that chromatic
yellow and blue mixture with the value of +b from 0 to +60 for yellow color and the value
–b from 0 to -60 for blue color. The colour reading was measured twice at the equatorial region of each fruit and two sepals, and averaged to give a value
for each fruit and sepal. The results were presented as lightness L, where 15
0= black, 100= white color, ab ratio and hue angle h
o
with red-purple at an angle of 0
o
, 90
o
representing yellow color, and 180
o
bluish-green color Palapol et al., 2009. Hue angle was calculated using the following formula:
Hue angle h
o
= arctan ba
3.3.2. Chemical Attributes
Kategori