冷冻猪肉欧姆加热解冻电势梯度与尺寸对解冻效果的影响

摘要

欧姆加热解冻是一种潜力很大的解冻方法.试验中研究冻结物料的尺寸、电势梯度对解冻时间、解冻速率、失水率、解冻均匀性和能量利用率的影响.选用尺寸不同的冻猪肉进行了解冻试验,尺寸分别为直径3、4、5 cm,长度为6 cm.解冻时从中心温度-18～5℃.试验过程中,变换解冻材料中的电势梯度,分别为20、30、40V/cm.结果表明:电势梯度和尺寸对解冻均匀性、失水率、能量利用率的影响不大.电势梯度和样品尺寸对解冻时间的影响较明显,电势梯度变大,解冻时间变小,尺寸增大,解冻时间变长.电势梯度和尺寸对解冻速率的影响分为两个阶段.电势梯度和尺寸对内部冻结温度以下的解冻速率影响不明显.在内部冻结温度以上,电势梯度增大,解冻速率变大,解冻加快,样品尺寸变大,解冻速率降低.欧姆加热解冻较传统解冻中的水解冻具有很大的优势.%The ohmic heating is a great potential thawing method.In this experiment,we studied the effects of freezing size and voltage gradient on the thawing time,thawing rate,water loss rate,thawing temperature homogeneity and energy utilization rate.The frozen pork were cut into 3 cm,4 cm and 5 cm diameters and 6 cm long,and thawing temperatures were set from-18 ℃ to 5 ℃.The tests were performed under different voltage gradient at 20,30,40V/cm.The results showed that there were not significant effects of voltage gradient and size on the temperature homogeneity,thawing loss rate and energy utilization rate.However,the voltage gradient and sample size had great influence on the thawing time.In detail,thawing time was decreased with the increase of voltage gradient,and increased with sample size.The effects of voltage gradient and size effects on thawing rate were divided into two stages.Below the pork freezing temperature,the voltage gradient and pork size had little influence on the thawing time; above the initial freezing temperature,with the voltage gradient increased the thawing rate increased,but with size increased,the thawing rate was decreased,obviously.Ohmic heating method has great advantages than traditional water thawing method.