不同形状尺寸冷冻牛肉的射频解冻均匀性探究

分别选取不同形状、厚度、底面积和放置方式的8种冷冻牛肉样品,采用频率为40.68 MHz的小型射频解冻炉进行解冻试验;基于试验数据,建立并求解计算机模型,预测样品的解冻升温速率和温度分布,并计算其解冻均匀性系数。结果表明,模拟计算得到的温度值与试验值契合度较高;所有牛肉样品的解冻速率整体上呈线性上升的趋势(相变温度区上升较缓慢)。厚度大的样品解冻速度快,但解冻均匀性较差;相同厚度的样品,底面积越大,解冻速度越慢,解冻均匀性较好;当样品垂直放置时,长方体样品出现严重过热现象,最高温度达到了55.2℃,解冻均匀性较差,而圆柱体样品的最高温度为36.6℃,解冻均匀性相对较好。

Study on the uniformity of frozen beef with various sizes and shapes thawed by radio frequency

To investigate the effects of geometric parameters on uniformity of frozen beef thawed by radio frequency(RF),frozen beef samples with 8 different shapes,thickness,bottom areas and placements were thawed in a RF oven(40.68 MHz)respectively for determining the thawing uniformity.Meanwhile,a computer model was established and utilized to predict the thawing rate and temperature distribution of the samples.The predicted temperature distribution showed a good agreement with the experimental results.The general thawing rates of all beef samples are constant and then decreased gradually as reaching the phase change temperature zone.Samples with larger thickness showed a higher thawing rate,but a worse thawing uniformity.For the samples with the same thickness,the larger the bottom area was,the slower thawing rate was.When placed vertically,the cuboid sample was more seriously overheated,and the maximum temperature reached 55.2℃,which represented a poor thawing uniformity.The maximum temperature of the cylinder sample was 36.6℃after RF tempering with relatively better thawing uniformity.