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標題: 荔枝乾燥之基礎研究
Fundamental Studies on Litchi Mechanical Drying
作者: 吳慶源
Wu, Ching-Iuan
關鍵字: Fruit-Lichi;荔枝;Mechanical Drying;Thin-Layer;乾燥;薄層
出版社: 農業機械工程學系

This work is to find an optimal drying process for afruit-
Lichi. We first investigate the blanching and coolingprocesses
for this fruit. The basic drying propertiesare obtained by
using a single temperature hot air method. These results are
then used to build a model for a mutiple temperature drying
process. The best blanching and cooling conditions of hot water
100℃ ,30" immediately followed by 200" in icy water are
demonstrated. These conditions can better maintain the shell
color of the fruit. A better drying process sequence of 45℃, 5
hours +50℃, 5 hours + 55℃, 5 hours + 60℃, 10 hours+65℃, 75
hours is also obtained. This process can save about 20 hours in
drying time when compared to the traditional method. It can
also obtain almost 100% yield and increase the quality of the
product. The dried fruit has the wet basismoisture content
between 17% and 25%. From the mass-energy conservation
equation, the calculated drying efficiency isabout 12% for the
on site stationary type drying machine. The single and multiple
temperature drying processes per- formed in the laboratory are
in consistence with the thin layer drying model derived from
Newton's cooling law. The moisture content of the fruit during
the drying process canbe precisely predicted fromthe equation
derived from thissemi-theoretical model.When applying the deep
layer drying model for the on site drying machine, we found it
cannot accurately predict the moisture content in the deep
layer of the fruit. The model gives 34hours longer time to
reach the 25% wet basis moisture content in the top layer
compared tothe actual data.
Appears in Collections:生物產業機電工程學系

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