通电加热下频率、温度对草鱼鱼块和鱼皮电导率的影响

Effects of frequency and temperature on the electrical conductivity of grass carp( Ctenopharyngodon idella) fillets and skin under ohmic heating

为探索通电加热作为淡水鱼类加工方式的可行性,以草鱼为研究对象,采用LCR测量仪,测定了经50 Hz,20 V交流电加热后,草鱼鱼块(并联、串联)、碎鱼肉、带皮鱼块样品在10~80℃温度范围、50~20 k Hz频率范围内的阻抗值,并计算样品电导率。实验结果表明,三种样品(并联及串联鱼块、碎鱼肉)的电导率均呈现出随频率增大而增大、随温度升高而升高的趋势,其中,受鱼块内部膜方向的影响,并联、串联样品电导率有显著差异(p<0.05);碎鱼肉样品消除了鱼肉内部膜的影响,其电导率值介于并联、串联样品之间。带皮鱼块样品由于鱼皮的存在,比起其他样品有不同的电导率值,鱼皮平行于电流放置时电导率值高于鱼皮垂直电流放置的值。

To verify the feasility of ohmic heating（ OH ）as a food thermal processing method for fl＇eshwater fish,grass carp, whith is one of the fimr domestic Chinese earps, was used as the object.The impedanc.e of grass carp fillets （ parallel, series） , minced fish and samples with skin were measured with a I,CR meter under 50 Hz-20 kHz after being heated via 50 Hz,20 V ahernating current within a temperature range of 10-80 ℃, afterwards the electrical conductivity （EC）of all the samples were aleulated and analyzed.The results showed that all samples displayed a tendency that EC increased with rising temperature and frequency.To fillets samples,due to the existence of memlJrane and its different direction against the electric current,there was significant difl＇erence between EC of parallel and series samples （p 〈 0.05 ）.The EC of mineed fish was among the value of parallel amt series samples with eliminating the influence of muscle membrane.The sample with skin showed distinct range of EC when compared with other groups of samples, whieh was influenced by skin, and electrical conductivity was higher when the skin was parallel to the current.