Abstract:Microwave vacuum drying technology was used to dry the raw material of water chestnut chips.The effects of microwave power，drying temperature，vacuum degree，and slice thickness on the color difference value，total sugar content，and crispness of water chestnut crisps were investigated，and the drying process was optimized by a response surface test.The moisture changes during the drying process of water chestnut crisps were studied by low?field nuclear magnetic resonance technology.The results showed that the optimal process of microwave vacuum drying of water chestnut crisps was as follows：microwave power of 2.0 kW，dry?ing temperature of 71 ℃，vacuum degree of -95 kPa，and slice thickness of 3.1 mm，and the color difference value，total sugar content，and crispness of the obtained products were 3.42，50.51 mg/100 g，and 464.96 g，respectively.The products were white in color and luster，crispy，and tasty，with a strong water chestnut fla?vor.The results of the low?field nuclear magnetic resonance test showed that there were mainly three states of water inside the water chestnut slices，namely，free water，non?flammable water，and combined water，among which the free water accounted for a relatively high proportion，and the combined water and the non?flammable water had a relatively low proportion.In addition，when the drying end point was reached in the optimal pro?cess，the free water was completely removed，and there remained only a small amount of non?flammable water and combined water.