temperature. Instead, brown spots on fruit skin were observed at storage day 8 and the spots were gradually enlarged up to the end of storage Appendix 19.
4.2. Chemical Changes of Mangosteen Fruit
4.2.1. Total Soluble Solids TSS
Total soluble solids of the fruit are considered one of the basic criteria for quality evaluation. Total soluble solids of mangosteen fruit during storage
decreased linearly over storage time Figure 18, 19. CoSO
4
did not affect TSS at all observed days Appendix table 14. At day 12 response of CPPU 30 ppm was
the same with control, but significantly different from CPPU 10 ppm and CPPU 20 ppm. CPPU 30, 10 and 0 ppm gave the same response, and statistical different
from CPPU 20 ppm at day 16. The reduction of total soluble solids was around 4- 5 in all treatments at the end of storage Appendix table 14. According to
Palapol et al. 2009, TSS of mangosteen harvested at stage 1 was around 15 and linearly increased to 17 at stage 5 and 6 during storage at 25
o
C. The findings revealed that mangosteen fruit underwent fast physiological changes
under room temperature. However, those changes become very slow when fruit were stored at 15
o
C as indicated in our results. Generally, TSS increases during ripening process and tends to decrease during prolonged storage which was
caused by the breakdown of simple sugar content into alcohol, aldehide, and amino acids Winarno and Aman, 1981. As reported in litchi fruit, concentrations
of ascorbic acid, phenols, sugars and organic acids decrease during storage Holcroft and Mitcham, 1996; Chen et al., 2001.
Figure 18. Changes in total soluble solids of mangosteen fruit treated with CPPU during storage.
Figure 19. Changes in total soluble solids of mangosteen fruit treated with CoSO
4
during storage.
4.2.2. Titratable Acidity TA
Titratable acidity in mangosteen fruit tended to be fluctuated during storage time Figure 20, 21. CPPU showed significant effect on the reduction of
titratable acidity at day 14, day 16, and day 30 with CPPU 20 ppm, and 30 ppm being the most effective. The effect of CoSO
4
was observed at day 8, while other observed days showed no significance at all applied concentrations Appendix
table 15. The results revealed that titratable acidity of mangosteen fruit was only 2
4 6
8 10
12 14
16 18
20
4 8
10 12
14 16
18 24
30
T ot
al sol u
b le soli
d s
°B rix
Storage time days
0 ppm 10 ppm
20 ppm 30 ppm
2 4
6 8
10 12
14 16
18 20
4 8
10 12
14 16
18 24
30
T ot
al solu
b le
soli d
s
o
B rix
Storage time days
0 ppm 500 ppm
1000 ppm 2000 ppm
slightly reduced during 30 days of storage. The finding was similar with Palapol et al. 2009, who reported that TA in mangosteen was 0.77 gram per 100 mL at
stage 1 and slightly decreased at stage 6 during storage at 25
o
C. In mango fruit, titratable acidity decreased with increased storage time Abbasy et al., 2009.
Increased activity of citric acid during ripening or reduction in acidity may be due to their conversion into sugars and their further utilization in the metabolic
processes of the fruit. The decreased acidity during storage demonstrated fruit senescence as reported by El-Ghaouth et al. 1991 and Garcia et al. 1998.
Figure 20. Changes in titratable acidity of mangosteen fruit treated with CPPU during storage.
Figure 21. Changes in titratable acidity of mangosteen fruit treated with CoSO
4
during storage. 0,0
0,1 0,2
0,3 0,4
0,5 0,6
0,7 0,8
4 8
10 12
14 16
18 24
30
T itr
at ab
le ac
id ity
Storage time days
0 ppm 10 ppm
20 ppm 30 ppm
0,0 0,1
0,2 0,3
0,4 0,5
0,6 0,7
0,8
4 8
10 12
14 16
18 24
30
T itr
at ab
le ac
id ity
Storage time days
0 ppm 500 ppm
1000 ppm 2000 ppm
4.2.3. TSSTA Ratio
