Analysis of Goat Milk by Near-Infrared Spectroscopy

Abstract

The objective of this study was to determine protein, fat, lactose, total solids, non-fatty solids contents, freezing point, titratable acidity and pH using Fourier transform near infrared spectroscopy (FT-NIR). Sixty samples of goat milk were used to calibrate the instrument by the partial least squares (PLS) method. The spectra were measured on the integration sphere in the reflectance mode with the use of a 0.1 mm wide transflectance cell. The following statistical values were obtained: correlation coefficient (R) = 0.920 and standard error of calibration (SEC) = 0.094 for protein, R = 0.951 and SEC = 0.124 for fat, R = 0.997 and SEC = 0.011 for lactose, R = 0.940 and SEC = 0.260 for total solids, R = 0.873 and SEC = 0.159 for non-fatty solids, R = 0.935 and SEC = 0.003 for freezing point, R = 0.952 and SEC = 0.295 for titratable acidity and R = 0.835 and SEC = 0.057 for pH. The calibration models developed were verified by cross validation. The study showed that FT-NIR is a potentially useful technique for evaluating the composition of goat milk.