Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/35517
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
摘要: 
本研究旨在尋求荔枝乾燥最佳模式,首先探討殺菁冷卻條件,同時以
實驗室單溫乾燥獲得的荔枝乾燥基本特性,來建立多段溫度乾燥模式。
經試驗結果,最佳的殺菁冷卻條件為以100℃熱水殺菁30秒後立刻用冰
水冷卻200秒,可保持果殼之顏色;最佳乾燥溫度條件為45℃-5小時+45
℃-5小時+50℃-5小時+55℃-5小時+60℃-10小時+65℃-75小時,此模式應
用於產地乾燥機進行荔枝乾燥,比傳統方法節省乾燥時間約20小時,成品
率幾達100%並提高品質,乾果濕基含水率介於17%∼25%之間。由質能
平衡方程式分析,本靜置式乾燥機乾燥效率平均約12.4%。實驗室單溫及
多段溫度乾燥結果與牛頓冷卻定律所建立之薄層乾燥模式甚為吻合,此半
理論模式得到之含水率變化方程式,可準確預測乾燥過程中荔枝含水率值
之變化;同時以深層乾燥模式應用於產地靜置式乾燥機乾燥之探討,發現
深層乾燥模式並不能準確的預估高深度層之荔枝含水率變化,最上層達濕
基含水率25%之預估時間比實際值落後約34小時。

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.
URI: http://hdl.handle.net/11455/35517
Appears in Collections:生物產業機電工程學系

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