苹果汁电导率及介电损耗因子影响因素的研究

Influencing Factors of Conductivity and Dielectric Loss Factor in Apple Juice

本文研究了苹果汁的电导率与可溶性固形物含量、温度、粘度和NaCl浓度等因素的关系,并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苹果汁的介电损耗因子。结果表明,苹果汁的电导率随可溶性固形物含量的增加呈先增大后减小的抛物线趋势,随温度线性增大,粘度大小对电导率的影响很小,添加少量NaCl苹果汁电导率成倍增大。借助SPASS数据分析软件,得出电导率同可溶性固形物含量、温度的非线性回归方程:σ=-28.69C2+17.292C+0.02T+0.135,R2为0.974,拟合度良好。通过计算获得苹果汁在不同频率下(13.56、27.12、40.68 MHz)与离子介导相关的介电损耗因子。这些结果和数据,可为欧姆和射频加热技术用于苹果汁生产提供基础数据支持。

The relationship between electrical conductivity and factors such as soluble solids content, temperature, viscosity and NaCl concentration was studied. Dielectric loss factors interrelated to ionic conductivity of apple juice under different frequencies was calculated according to the equation of electrical conductivity and dielectric loss factors. The results showed that electrical conductivity appeared paracurve trend which increased first and then decreased with the increase of soluble solids content of the apple juice; it was increased linearly with temperature and remarkably increased with adding little of NaCl; viscosity had little effect on electrical conductivity. Using statistical package social sciences （SPSS） data analysis software, non-linear regression equation of temperature-concentration dependent electrical conductivity for apple juice was obtained, which was σ=-28.69C2＋17.292C＋0.02T＋0.135 with R2 of 0.974, showing quite high fitting degree. The results provide basic data for the application of ohmic and radio frequency heating in industrial manufacturing of apple juice.