| Summary: | 碩士 === 國立勤益科技大學 === 冷凍空調系 === 98 === The increasingly severe global warming is leading to abnormal weathers, frequent occurrence of earthquakes and floods, which in turn, result in crop failure. Rice is one of the staple food in Oriental diet, hence, various techniques have been developed to extend the storage time of rice, while maintaining its original flavors and nutrients. Among the drying method, vacuum freeze drying is a kind of food processing method that integrates vacuum technology, freezing technology, and drying technology, which can preserve food color, aroma, and taste, with lightweight and good rehydration. This study employed the vacuum freeze drying principle to dehydrate rice by four different freeze drying methods, and conducted rehydration test to restore the original rice moisture and taste in the same time period. The results were analyzed to analyze the effects of different freeze drying methods on the rehydration ratio of rice. Experiments confirmed that the slower ramping rate of heating shelf temperature in freeze drying process leads to better water absorption and taste.
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