中文摘要：

真空冻干水分的在线监测对进行低能耗冻干工艺的优化有着重要意义，因此在探索应用介电常数检测真空冷冻水分时需要研究温度对果蔬介电常数的影响。现有介电特性测量装置需要加长导线将探针置入冻干箱内实现在线测量，导致测量结果不稳定，所以采用自制的无线测量装置检测果蔬介电特性。选取苹果和土豆为试材，在试材含水率为10％、20％、30％、40％、50％时，测试不同冻干温度下的相对介电常数。试验结果表明：在相同含水率时，温度是影响果蔬相对介电常数的关键因素，且含水率越高时温度对果蔬相对介电常数影响越大。

英文摘要：

Online monitoring of water in the process of vacuum freeze-drying is very important for reducing energy con- sumption of freeze-drying , therefore it is essential to research the influence of the temperature on the relative dielectric constant , while we explore the moisture content monitoring based on relative dielectric constant during freeze -drying .The existing dielectric property measure devices need a longer wires put probe into freeze-drying box to realize online measure,which causes the measurement is not stable ,so this paper uses self-made wireless measure device which realize the relative dielectric constant of fruit and vegetable detect during freeze-drying .Apple and potato were selected as ex-perimental materials , when the moisture content of material was 10%, 20%, 30%, 40%and 50%, measure the rela-tive dielectric constant at different freeze-drying temperature .The test result shows： under the same moisture content , temperature is the key factor to influence the relative dielectric constant of fruit and vegetable , and the higher of moisture content the greater of temperature influence on the relative dielectric constant of fruit and vegetables .