Application of FTIR-ATR spectroscopy and chemometrics for the detection and quantification of lard oil in bovine milk fat

Abstract

Bovine milk fat (BMF) is considered as high nutritional fat because it contains fatty acids, lipid derivatives, and fat-soluble vitamins such as vitamin A, D, E, and K which are beneficial for human health. As a consequence, the price of BMF is higher among other fats. Fraudulent practices such as substitution or replacement with a lower price of fat and oil such as lard oil (LO) are potential to get more economic benefits. Moreover, lard is a non-halal substance which is prohibited to consume especially for Muslim. Therefore, the development of a rapid and accurate method for authentication of BMF from LO is highly required. The objective of this study was to develop Fourier transform infrared (FTIR) spectroscopy and chemometrics of multivariate analysis for detection and quantification of LO in binary mixtures with BMF. Samples were prepared by mixing BMF with adulterant of LO in the concentration range of 0-100% of LO. Each sample was scanned using FTIR attenuated total reflectance (ATR) spectroscopy in three replicates at the wavenumber region of 4000-650 cm-1 . The FTIR spectra of BMF and LO has a different pattern at the wavenumber region of 1510-900 cm-1 . Qualitative chemometrics analysis was performed using discriminant analysis (DA), meanwhile, quantitative chemometrics analysis was carried out using partial least square (PLS) and principal component regression (PCR). Results showed that discriminant analysis using normal FTIR spectra at the wavenumber of 3098-669 cm-1 perfectly classified authentic BMF and adulterated BMF with LO. In addition, PLS calibration of FTIR spectra at the wavenumber combination of 3033-2770 cm-1 and 1510-692 cm-1 using first derivative spectra was chosen for quantification of LO in BMF with a high value of R2 (>0.99) in calibration and validation models and lower RMSEC (0.631) and RMSEP (1.94). It can be concluded that FTIR spectroscopy coupled with chemometrics of discriminant analysis and partial least square considered as a rapid and accurate method for the detection and quantification of lard oil in bovine milk fat.