Near-infrared spectroscopy for biomonitoring: influence of somatic cell count on cow's milk composition analysis

The influence of milk with high somatic cell count on the accuracy of near-infrared spectroscopic determination of fat, protein and lactose content of non-homogenized milk was investigated. Transmittance spectra of 258 milk samples were obtained by the NIRSystem 6500 spectrophotometer in the 700-1100 nm region. The best accuracy for fat, protein and lactose content determination was found for calibration equations, derived from samples with low somatic cell count (SCC). The standard error of prediction increased and the correlation coefficient decreased significantly, both when equations, derived from samples with low SCC milk were used to predict the content of the examined components in samples with high SCC, and when equations, obtained for samples with high SCC were used to predict the content of the components in samples with low SCC. Therefore, milk samples with high SCC in a data set used for calibration or prediction highly influenced the accuracy of fat, protein and lactose determination. (C) 2001 Elsevier Science Ltd. All rights reserved.