Apart from SSC, pH of all the honeydew samples was decreased
throughout the storage period (Fig. 1d). All of the treated samples
had slightly lower pH compared to control sample at day 1 and day
4 of storage. After day 4, no significant difference of pH was found
between control and treated samples. The difference of pH at day 1
and day 4 could be partially due to the pH difference of coating
solutions (deionized water: pH 7.00; 2% chitosan: pH 5.07; 1%
CaCl2: pH 6.06; 1% CaCl2 þ 2% chitosan: pH 4.32). According to
Hodges (2003), pH of postharvest produce can be affected by
oxidative stress, environmental stress and harvest stress (e.g.,
weight loss), which results in disruption of membrane integrity as
well as cellular activities. The significant decrease in pH observed in
control group could be largely due to these stresses which had less
effect on treated samples (Hodges, 2003). These stresses also
caused a reduction of ATPase pumping capacity, thus decreasing
the cellular pH. However, TA was significantly increased in control