The freeze-dried pumpkin flours were significantly higher
(p 0.05) in a* values than those of the hot-air oven dried pumpkin
flours (Table 1). These results showed that freeze-dried pumpkin
flour samples were more red (indicated by higher a* value). This
fact is well documented in the articles written by Que et al. (2008)
and Garcia-Martinez, Igual, Martín-Esparza, and Martínez-
Navarrete (2013). Metabisulfite pre-treatment lead to a significant
decrease (p 0.05) in a* values of the samples. This result was
consistent with data previously obtained by Chen et al. (2007) who
reported that freeze-dried mango with soaking treatments
(NaHSO3) exhibited lower a* value than without soaking treatment.
In the present study, b* values of the samples with metabisulfite
pre-treatment are significantly lower (p 0.05) than those of the
samples without metabisulfite (Table 1). Similar results were also
determined from a study carried out by Chen et al. (2007).b* values
of the freeze-dried pumpkin flours showed less yellowness (indicated
by higher b* value) than those of the hot-air oven dried
pumpkin flours (p 0.05). Freeze drying (FD) reduced the
browning, preserved redness (indicated by higher a* value) and