The use of FTIR spectroscopy combined with pattern recognition and multivariate calibration for rapid authentication of Etawa goat milk from soymilk

Etawa goat milk (EGM) is valuable milk with a higher price compared to other kinds ofmilk. It is susceptible to being adulterated with low-priced milk for economical reasons.Therefore, the development of an analytical method for rapid authentication of EGM fromsoymilk (SM) is highly required. Fourier transform infrared (FTIR) spectroscopycombined with chemometrics was evaluated for rapid qualitative and quantitative analysisof SM in raw fresh EGM samples. Samples were prepared by mixing goat milk withsoymilk in several concentration levels ranging from 0-100% (v/v). FTIR spectra revealedthe differences between authentic and adulterated EGM samples in certain wavenumberregions. Linear discriminant analysis (LDA) at wavenumbers of 3000-750 cm-1 wassuccessfully used for discrimination between authentic and adulterated EGM samples. TheCooman plot showed a clear classification between pure and adulterated goat milksamples. Partial least square (PLS) using wavenumber combination of 3000-2800 cm-1and 1800-650 cm-1 as well as principal component regression (PCR) using wavenumber of3000-750 cm-1 has been successfully used for quantification of SM in EGM. However,PLS offered a better model for quantification with higher values of R2 calibration (0.9997)and validation (0.9992) and lower values of RMSEC (0.848) and RMSEP (1.19). It can beconcluded that this method is promising for the rapid authentication of goat milk samples.