近年来随着人们对乳制品需求的不断增加, 将复原乳冒充或添加在鲜乳中出售的现象也日益严重, 亟需简单、 快速的检测方法监测掺假行为。 利用同步荧光技术, 分别对两种鲜牛乳(未经杀菌的生牛乳和低温处理的巴氏杀菌乳)掺杂复原乳的情况进行了定性判别和定量分析。 以各类样本及全部样本的判别正确率作为定性判别模型的评价指标; 以相关系数(r)、 校正均方根误差(RMSEC)和预测均方根误差(RMSEP)作为定量分析模型的评价指标。 通过分析牛乳的三维荧光图谱确定同步荧光扫描的固定波长差Δλ值为80 nm; 在对图谱进行二阶求导后, 偏最小二乘-判别分析法(PLS-DA)对生鲜牛乳、 巴氏杀菌乳和复原乳的种类判别总正确率可达100%, 并且在判断两种鲜乳中是否添加复原乳时, 校正集样品的正确率均可达到100%, 预测集样品的正确率分别为75%和81.25%, 鲜牛乳和复原乳的种类判别模型, 以及鲜乳与掺假乳的定性判别模型均取得了良好的效果; PLS回归对同步光谱值与复原乳含量建立线性关系时, 两种鲜乳定量模型的r值分别为0.911 2和0.936 7, RMSEC分别为0.042 2和0.038 4, RMSEP分别为0.054 8和0.057 5, 鲜乳中复原乳含量的定量分析模型的r值均可达到0.9以上, 能对添加量较高的样品进行预测。 因此, 同步荧光技术可以较为准确、 快速的检测鲜牛乳中是否掺杂复原乳。

In the present research, synchronous fluorescence technique was used for qualitative and quantitative detection of reconstituted milk mixed into two kinds of milk samples, raw milk and pasteurized milk, respectively. The total accuracy of sample was used to evaluate the performance of the qualitative discrimination models. The correlation coefficient (r), the root mean square error of correction (RMSEC) and the root mean square error of prediction (RMSEC) were used to evaluate the performance of the quantitative analysis models. The constant wavelength difference (Δλ) between the excitation and emission scanning was determined to be 80 nm from three-dimensional fluorescence spectrum of milk. The total discrimination accuracy was 100% by partial least squares discrimination analysis (PLS-DA) for raw milk, pasteurized milk and reconstituted milk samples. When checking whether the raw milk and pasteurized milk were mixed with reconstituted milk, the total accuracy of calibration samples was 100% and the accuracy of prediction samples was 75% and 81.25%, respectively. The effects of qualitative discrimination models were satisfactory. The PLS regression was used for quantitative analysis of the reconstituted milk content mixed in raw milk and pasteurized milk. The correlation coefficients of actual values versus predicted values were 0.911 2 and 0.911 2, respectively. The RMSEC was 0.042 2 and 0.038 4, respectively. The RMSEP was 0.054 8 and 0.057 5, respectively. The correlation coefficients of quantitative analysis models could reach up to 0.9. The results showed that synchronous fluorescence technology could be applied for rapid detection of reconstituted milk mixed in fresh milk.