of phenolic substances during drying at 70 C. These authors also
reported that the degree of heating could be an important factor
contributing to high total polyphenol content of pumpkin flour.
Piga, Alessandra, and Giampaola (2003) reported similar results
for prunes from plums.
The phenolics of the samples with metabisulfite application
were significantly (p 0.05) higher than those of the samples
without metabisulfite pre-treatment (Table 3). Soaking in metabisulfite
solution might have a protective effect for phenolic compounds.
Similar results have been reported in Taiwanese mango
(Chen et al., 2007). Mir, Hussain, Fouzia, and Rather (2009) also
indicated that the antioxidant action of sulfur can help in the
preservation and stabilization of carotenoids. According to Chen
et al. (2007), soaking in antioxidants, such as NaHSO3 prior to
drying of Taiwanese mango was shown to produce a higher yield of
neoxanthin than without soaking.
Phenolics bioaccessibility of pumpkin flours was investigated in
order to assess pumpkin flour as sources of accessible phenolics
(Table 3). The content of bioaccessible phenolics ranged from 263 to
457 mg of GAE 100 g1 DW in the samples. The highest bioaccessible
phenolics (457 mg of GAE 100 g1 DW) and phenolic
bioaccessibility values (37%) were observed in hot-air oven dried
pumpkin flour with metabisulfite pre-treatment. Metabisulfite
application caused a significant (p 0.05) increase in bioaccessible
phenolics of pumpkin flours. Bioaccessible phenolics of freezedried
pumpkin flour samples were significantly (p 0.05) lower
in comparison with hot-air oven dried pumpkin flours. There is no
study on phenolic bioaccessibility derived from pumpkin and its
products to compare.