Frequency- and temperature-dependent dielectric properties of fruit juices associated with pasteurization by dielectric heating
Frequency- and temperature-dependent dielectric properties of fruit juices associated with pasteurization by dielectric heating
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DOI：
10.1016/j.jfoodeng.2011.10.005
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发表时间：
2012-03
影响因子：
5.5
通讯作者：
Xinhua Zhu;Wenchuan Guo;Xiaoling Wu
中科院分区：
文献类型：
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作者：
Xinhua Zhu;Wenchuan Guo;Xiaoling Wu
研究了 15–95°C、20 至 4500MHz 范围内苹果、梨、橙子、葡萄和菠萝汁的介电特性。果汁的介电常数ε′随着频率的增加而降低。损耗因数 ε'' 随着频率的增加而减小，在大约 1000 到 3000MHz 之间达到最小值，具体取决于温度，然后随着频率的增加而增加。该转折点的频率增加，而最小ε”随着温度的升高而降低。在低于约1000MHz时，ε″值随着温度的升高而增加，而在3000MHz以上时，随着温度的升高而降低。介电常数随着温度的升高而持续线性降低。开发了介电特性对温度的依赖性的线性或多项式相关性。所有果汁的功率穿透深度都随着频率的增加而降低。在较低频率下，深度随着温度的增加而减小，而在 3000MHz 以上则随着温度的增加而增加。研究中获得的介电特性为介电加热果汁巴氏灭菌提供了重要参数。
Dielectric properties of apple, pear, orange, grape and pineapple juices were studied from 20 to 4500MHz at 15–95°C. The dielectric constants ε′of fruit juices decreased as frequency increased. The loss factors ε″decreased with increasing frequency to a minimum between about 1000 and 3000MHz, depending on temperature, and then increased as frequency increased. The frequency of that turning point increased, whereas the minimum ε″decreased with increasing temperature. The ε″values increased with increasing temperature below about 1000MHz, and decreased with increasing temperature above 3000MHz. Dielectric constants decreased consistently and linearly with increasing temperature. Linear or polynomial correlations for the dependence of dielectric properties on temperature were developed. The power penetration depth of all fruit juices decreased with increasing frequency. The depth decreased as temperature increased at lower frequencies and increased with temperature above 3000MHz. The dielectric properties obtained in the study provide important parameters for juice pasteurization by dielectric heating.