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

Abstract

Etawa goat milk (EGM) is valuable milk with a higher price compared to other kinds of milk. 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 from soymilk (SM) is highly required. Fourier transform infrared (FTIR) spectroscopy combined with chemometrics was evaluated for rapid qualitative and quantitative analysis of SM in raw fresh EGM samples. Samples were prepared by mixing goat milk with soymilk in several concentration levels ranging from 0-100% (v/v). FTIR spectra revealed the differences between authentic and adulterated EGM samples in certain wavenumber regions. Linear discriminant analysis (LDA) at wavenumbers of 3000-750 cm-1 was successfully used for discrimination between authentic and adulterated EGM samples. The Cooman plot showed a clear classification between pure and adulterated goat milk samples. Partial least square (PLS) using wavenumber combination of 3000-2800 cm-1 and 1800-650 cm-1 as well as principal component regression (PCR) using wavenumber of 3000-750 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 be concluded that this method is promising for the rapid authentication of goat milk s