Application of attenuated total reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR) in MIR range coupled with chemometrics for detection of pig body fat in pure ghee (heat clarified milk fat)

Pure ghee is superior to other fats and oils due to the presence of bioactive lipids and its rich flavor. Adulteration of ghee with cheaper fats and oils is a prevalent fraudulent practice. ATR-FTIR spectroscopy was coupled with chemometrics for the purpose of detection of presence of pig body fat in pure ghee. Pure mixed ghee was spiked with pig body fat @ 3, 4, 5, 10, 15% level. The spectra of pure (ghee and pig body fat) along with the spiked samples was taken in MIR from 4000 to 500 cm(-1). Some wavenumber ranges were selected on the basis of differences in the spectra obtained. Separate clusters of the samples were obtained by employing principal component analysis at 5% level of significance on the selected wavenumber range. Probable class membership was predicted by applying SIMCA approach. Approximately, 90% of the samples classified into their respective class and pure ghee and pig body fat never misclassified themselves. The value of R-2 was >0.99 for both calibration and validation sets using partial least square method. The study concluded that spiking of pig body fat in pure ghee can be detected even at a level of 3%. Practical applications: The adulteration of pure ghee with cheaper animal body fats is a menace and reports pertaining to the same appear in newspaper frequently. Lard, due to the presence of higher amount of fat, is a choice of unscrupulous manufacturers to be used for adulteration purposes. Thus, techniques for detection of presence of lard in pure ghee needs to be investigated. In this context, the present study was envisaged with the aim to detect presence of pig body fat in pure ghee by using ATR-FTIR It can be seen that the strong absorbance at the specific wavenumber ranges (3030-2785, 1786-1680, 1490-919 cm(-1)) are seen in case of pig body fat and the samples spiked with the same and can be used as the regions for detecting the presence of pig body fat in pure ghee. The results of PCA, SIMCA and PLS statistically prove that the said region is good for detecting the presence of pig body fat in ghee, indicating the utility and robustness of the FTIR technique. (C) 2017 Elsevier B.V. All rights reserved.