Authentication analysis of goat milk from cow milk using Fourier Transform Infrared spectroscopy and chemometrics

The authentication of higher quality milk such as goat milk (GM) from the lower price of cow milk (CM) is a big issue in the milk industry, because unethical producers may get economic profits from the adulteration practice. This study intended to apply Fourier Transform Infrared (FTIR) spectroscopy and chemometrics for the authentication analysis of GM from CM. The characterization of CM and GM was performed by determining fatty acid composition using gas chromatography. The binary mixtures of GM and CM were prepared for making calibration and validation models and were subjected to FTIR spectral measurement using an attenuated total reflectance (ATR) accessory. The model was optimized by selecting multivariate calibrations of partial least square regression (PLSR) and principal component regression (PCR) along with spectral modes (normal and derivatives) and wavenumbers regions. The results showed that absorbance values at 2nd derivative spectra at wavenumber regions of 1500-800 cm-1 could provide the best accuracy and precision of the developed model. Principal component analysis (PCA) at selected wavenumbers and linear discriminant analysis (LDA) at 3800-800 cm-1 could discriminate authentic GM and GM adulterated with CM without any misclassification objects observed. It concluded that FTIR spectra combined with chemometrics techniques could be used as a reliable method for the authentication analysis of milk products.