Determination of fat, protein, and total solids in cheese by near-infrared reflectance spectroscopy

Near-infrared reflectance (NIR) spectroscopy was used to analyze fat, protein, and total solids in cheese without any sample treatment. A set of 92 samples of cow's milk cheese was used for instrument calibration by principal components analysis and modified partial least-square regression. The following statistical values were obtained: standard error of calibration (SEC) = 0.388 and squared correlation coefficient (R2) = 0.99 for fat, SEC = 0.397 and R2 = 0.98 for protein, and SEC = 0.412 and R2 = 0.99 for total solids. To validate the calibration, an independent set of 25 cheese samples of the same type was used. Standard errors of validation were 0.47, 0.50, and 0.61 for fat, protein, and total solids, respectively, and R2 for the regression of measurements by reference methods versus measurements by NIR spectroscopy was 0.98 for the 3 components.