为了了解生长发育后期梨的介电特性与生理特性和内部品质的关系，采用同轴探头技术测量了生长发育后期2个月内梨在20~4500 MHz间的介电参数（相对介电常数 和介质损耗因子 ），同时测量了梨的生理参数（乙烯释放量和呼吸强度）以及内部品质参数（可溶性固形物含量SSC、硬度和含水率）。结果表明：在所测频率范围内， 随频率的增加而减小， 在25 MHz附近存在极大值，在1300 MHz附近存在极小值。 和 随时间的推移先减小后增大。糖度和硬度随时间的推移呈下降趋势。呼吸高峰出现于乙烯释放高峰之前，且乙烯释放高峰的出现时间与介电参数由减小到增大的转折点相同。介电参数与SSC和硬度之间没有明显的线性关系。研究说明，梨的介电特性是生理特性的反映，可以根据介电参数值判断梨的成熟情况，但是单一频率下的介电参数值很难用于评价梨的内部品质。

To understand the relationship of dielectric properties and physiological properties with the internal qualities of pears during the late growth stage, the open-ended coaxial-line probe technique was used to measure the permittivities (relative dielectric constant and dielectric loss factor ) of pears over the frequency range of 20~4500 MHz during the last 2 months of the ripening period, along with the physiological properties (amount of released ethylene and respiration intensity) and internal qualities (soluble solid content [SSC], firmness, and moisture content). Over the frequency measurement range, decreased with increase in frequency, and had maximum and minimum values at approximately 25 MHz and 1300 MHz, respectively. Over time, and increased after the initial decrease, and sugar content and firmness decreased generally. The respiration peak occurred before the peak of released ethylene, and the time when the peak of released ethylene appeared was the same as the turn point when permittivities changed from decreasing to increasing. Apparent linear relationships of the permittivities with SSC and firmness were not found. The results indicate that the dielectric properties of pears are the reflection of physiological properties and that the maturity of pears can be determined on the basis of values of permittivities. However, it is difficult to use the value of a permittivity at a single frequency to assess the internal qualities of pears.

国家自然科学基金资助项目（31171720）