The effect of blanching on drying and rehydration characteristics
of sweet potato slices was investigated. The blanched
samples have shorter drying times (hence higher
drying rates) compared to control samples. Moreover,
blanched samples have higher rehydration ratio than control
samples. Constant drying rate period was not observed, the
sweet potato drying occurring in the falling-rate period.
Drying data obtained were fitted to five thin-layer drying
models and goodness of fit determined using R2, P, v2 and
RMSE. The results showed that the change of moisture ratio
with drying time in the temperature range from 50 to 70C
can be successfully described by the logarithmic model (R2
0.9993–0.9999; P 0.8225–5.8800; v2 0.000007–0.000069;
RMSE 0.010032–0.023590). The effective moisture diffusivity
was computed from Fick’s second law, the values
of which varied between 9.323 9 10-11 and 1.758 9
10-10 m2/s, over the temperature range. The effective
moisture diffusivity increases as temperature increases.
Temperature dependence of the diffusivity values was
described by an Arrhenius-type relationship. The values of
activation energy of blanched and control samples found to
be 23.2 and 22.7 kJ/mol, respectively.
The effect of blanching on drying and rehydration characteristics
of sweet potato slices was investigated. The blanched
samples have shorter drying times (hence higher
drying rates) compared to control samples. Moreover,
blanched samples have higher rehydration ratio than control
samples. Constant drying rate period was not observed, the
sweet potato drying occurring in the falling-rate period.
Drying data obtained were fitted to five thin-layer drying
models and goodness of fit determined using R2, P, v2 and
RMSE. The results showed that the change of moisture ratio
with drying time in the temperature range from 50 to 70C
can be successfully described by the logarithmic model (R2
0.9993–0.9999; P 0.8225–5.8800; v2 0.000007–0.000069;
RMSE 0.010032–0.023590). The effective moisture diffusivity
was computed from Fick’s second law, the values
of which varied between 9.323 9 10-11 and 1.758 9
10-10 m2/s, over the temperature range. The effective
moisture diffusivity increases as temperature increases.
Temperature dependence of the diffusivity values was
described by an Arrhenius-type relationship. The values of
activation energy of blanched and control samples found to
be 23.2 and 22.7 kJ/mol, respectively.
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