Color stability.
The 50% propylene glycol dragon fruit peel was used to study its stability at various
condition including light 4°C, dark 4°C, light room temperature and dark room temperature.
The dragon fruit peel extract alone was compared with the extract addition with betel nut or
ginger extracts. Color change of the extract sample was evaluated by colorimeter and
interpreted as total color difference (dE*). The dE* (∆E*
= [(∆L*
)
2
+ (∆a*
)
2
+ (∆b*
)
2
]
½ ) is
based on L*,a*,b* color differences (Esquivel et al., 2007). As can be seen in Figure 2, the
dE* values of all extracts were not significantly change during storage in all samples.