915MHz和2450MHz频率下温度和盐溶液浸渍对青鱼介电特性的影响

Effect of temperature and salt solution soakage on dielectric properties of black carp at 915MHz and 2450MHz

采用同轴探针法测定了频率915、2450MHz,温度范围10～90℃下,经浓度1%、2%、3%、4%食盐溶液浸渍的生鲜青鱼鱼片和预加热青鱼鱼片的介电特性值,并应用DSC测定了样品肌动蛋白和肌球蛋白的热变性温度。考察了温度、频率、水分含量、食盐溶液浸渍和蛋白质热变性对样品介电常数、介电损失率和穿透深度的影响。结果显示,浸渍盐溶液的渗透使得样品介电行为在一定程度上接近于相应盐浓度的浸渍溶液。浸渍对样品介电常数影响较小,而对介电损失率变化较大。随温度的上升,因加热过程中蛋白质的热变性引起样品水分的流失,导致生鲜样品的介电常数值的减小趋势明显大于预加热样品。而经浸渍的生鲜样品的介电损失率增大趋势明显大于预加热样品,并随浸渍溶液含盐量增大而增大。应用二项式方程得出介电特性的回归预测方程。

The dielectric properties of raw and preheated black carp flesh at different temperatures （10-90~C）, different frequencies （915 and 2450MHz）,and different concentration （1% ,2% ,3% and 4%） of salt solutions soakage were determined using the coaxial line method. Temperatures of the denaturation of myosin and actin in the raw samples were monitored by differential scanning calorimeter （DSC）. The influences of temperature, frequency,moisture content,concentration of salt solutions,and protein thermal denaturation on dielectric constant,dielectric loss factor,and penetration depth were analyzed. Results showed that salt solutions soakage had more great influence on dielectric constant than that on dielectric loss factor. With increasing temperature,the dielectric constant of the raw samples decreased more sharply than that of the preheated samples,and the dielectric loss factor of soaked raw samples increased more quickly than that of the preheated samples,which was due to moisture loss during heating caused by protein thermal denaturation. The dielectric loss factor of samples increased with increasing of the salt concentration of solution. Changes in the dielectric properties of the samples at 915 and 2450MHz with increasing temperature were found to follow second order polynomial equations.