L* values of banana puree treated with PSE decreased less than that of potato, apple and
mushroom puree treated with PSE during storage for 2 hrs (Fig 2). The a* value of banana puree
treated with PSE increased less than that of potato puree during storage while the a* value of apple
and mushroom puree treated with PSE decreased after storage. The change of b* value of banana
and potato puree treated with PSE was less than that of mushroom and apple puree during storage.
The decrease of L* value means darker color. The increase of a* value means higher red
color, and the decrease of b* value means less yellow color. Thus, the decrease of L* and b* value
and the increase of a* value are related with a high browning value (Moline et al., 1999). The results
showed that the changes of L* and a* values in banana puree treated with PSE was lower than that of
the other vegetables and fruits as described above. This indicated that the increase of browning in
banana puree treated with PSE was less than that of the other puree during storage. PSE might be
due to more specific inhibition of PPO isoenzymes in banana than in the others. The PPO isoenzymes
in each plant were reported to be different (Labuza et al., 1990). The compounds in PSE that showed
the browning inhibitory effects may be phenolic compounds in pineapple shell which was a source of
0
3
6
9
12
15
0 5 10 15 20 25
time (hrs)
browing value
DW PSE PH
0
4
8
12
16
20
24
28
32
36
40
44
0 5 10 15 20 25
time (hrs)
browning value
DW PSE PH
0
3
6
9
12
15
18
21
24
27
30
33
0 5 10 15 20 25
time (hrs)
browning value
DW PSE PH
0
5
10
15
20
25
30
35
0 5 10 15 20 25
time (hrs)
browning value
DW PSE PH
A B
C D
phenolic compounds (Larrauri et al., 1996). Rohn et al. (2001) reported that phenolic compounds
from plants could prevent browning reaction. Iyengar and McEvily (1992) also found that aromatic
carboxylic acid of phenolic compounds could inhibit browning reaction as well.