Rodríguez-Otero J L, Hermida M
Universidade de Santiago de Compostela, Facultad de Veterinaria, Departamento de Química Analítica, Nutrición y Bromatología, Lugo, Spain.
J AOAC Int. 1996 May-Jun;79(3):817-21.
Fat, protein, and total solids in fermented milk were determined by near-infrared reflectance spectroscopy (NIRS). A set of 107 samples from diverse types of fermented milk (whole, skimmed, with added flavors, and without added flavors) were used to calibrate the instrument by modified partial least-square regression. Global calibration, using all samples, was more effective than specific calibrations using fewer samples of each type. Standard errors of a calibration were 0.071 for fat, 0.075 for protein, and 0.083 for total solids. Values of the correlation coefficient square (R2) were 0.997 for fat, 0.981 for protein, and 1.000 for total solids. Calibration was validated with an independent set of 34 samples of the same types. Standard errors of validation were 0.08, 0.14, and 0.25 for fat, protein, and total solids, respectively, and values of R2 for the regression of measurements by NIRS versus reference methods were 1.00 for fat and total solids and 0.94 for protein. When Standard 128 of the International Dairy Federation was used to compare NIRS results with those from reference methods, no significant differences were found (p = 0.05).
采用近红外反射光谱法（NIRS）测定发酵乳中的脂肪、蛋白质和总固形物含量。使用一组来自不同类型发酵乳（全脂、脱脂、添加风味剂和未添加风味剂）的107个样品，通过改进的偏最小二乘回归法对仪器进行校准。使用所有样品进行的全局校准比使用每种类型较少样品的特定校准更有效。校准的标准误差分别为：脂肪0.071、蛋白质0.075、总固形物0.083。相关系数平方（R2）值分别为：脂肪0.997、蛋白质0.981、总固形物1.000。使用另一组34个相同类型的独立样品对校准进行验证。验证的标准误差分别为：脂肪0.08、蛋白质0.14、总固形物0.25，NIRS测量值与参考方法回归的R2值分别为：脂肪和总固形物1.00、蛋白质0.94。当使用国际乳品联合会标准128将NIRS结果与参考方法的结果进行比较时，未发现显著差异（p = 0.05）。
