红枣汁电导率及介电损耗因子影响因素的研究

Studies on Influencing Factors of Electrical Conductivity and Dielectric Loss Factor of Jujube Juice

红枣含有丰富的营养成分,具有很高的营养价值。欧姆与射频加热技术在果汁浓缩、杀菌操作中具有巨大的应用潜力。物料电导率、介电损耗因子是这两种技术的重要参数。本文研究红枣汁的电导率与可溶性固形物含量、温度、黄原胶浓度和Na Cl浓度等因素的关系,通过电导率与介电损耗因子的关系,确定不同频率下与离子介导相关的红枣汁的介电损耗因子。试验结果表明,红枣汁的电导率随着可溶性固形物含量的增大而先增大后减小;随着温度的线性增大,黄原胶浓度对电导率的影响很小;添加少量Na Cl,红枣汁电导率增大好几十倍。通过计算获得红枣汁在不同频率(13.56,27.12,40.68 MHz)下与离子介导相关的介电损耗因子。本研究结果可为欧姆和射频加热技术用于红枣汁生产应用提供基础数据。

Jujube has very high nutritional value with rich nutrients. Ohmic and radio-frequency heating hold great potential applications in concentration and sterilization of fruit juices. Electrical conductivity and dielectric loss factor are important parameters for research and application of these technologies. The relationship between electrical conductivity and facts as soluble solids content, temperature, xanthan gum and Na Cl concentrations was studied. Dielectric loss factors interrelated to ionic conductivity of jujube juice under different frequencies were caculated according to the equation of electrical conductivity and dielectric loss factor. The results showed that with the increase of soluble solids content of the jujube juice, electrical conductivity first increased and then decreased. Electrical conductivity increased linearly with temperature. Xanthan gum concentration had little effect on electrical conductivity. Electrical conductivity increased remarkably with few added of Na Cl into jujube juice. Dielectric loss factors interrelated to ionic conductivity of jujube juice under different frequency（13.56, 27.12, 40.68 MHz） were calculated. The results and parameters provides basic data for the application of ohmic and radio frequency heating in industrial manufacturing of jujube juice.