基于生物阻抗特性的苹果新鲜度无损测定

Non-destructive Detection of Freshness Grade for Apple Fruit Based on Bio-impedance Properties

以红富士苹果为试材,在室温下贮存得到失重率0、5%、10%、15%和果心褐变果实,分别定义为1、2、3、4、5级新鲜度,采用LCR阻抗仪测定各等级共424个果实的14个生物阻抗参数在9个频率点下的126个特征值。通过稀疏主元分析-线性分类器(SPCA-LDC)模型试验,得出适宜的选样比例(训练样本数与测试样本数之比)为9∶1,主元数达到前39～45个时分级正确率达到最大值;构成至少39个主元的生物阻抗特征参数为44个;50次重复试验的分级正确率平均值为87.90%。

Bioimpedance properties of Fuji apple fruit with different freshness were investigated.Fruit with weight loss of 0,5%,10%,15% and core-browning under room temperature were chosen as samples corresponding to descending freshness grades of 1,2,3,4,5,respectively.126 observations of 14 bio-impedance parameters under nine frequencies of total 424 fruit from each grade were measured fruit by fruit with LCR impedance meter.Data were computed by using the sparse principal component analysis-linear classifier（SPCA-LDC） model.Results indicated that classification accuracy reached to maximum stably when the ratio of training sample to test sample of 9∶1 and former 39-45 principal component（PC） were adopted.The least 39 PCs were consisted of 44 from the 126 observations.Average rate of classification accuracy reached to 87.90% within 50 test repeats.