Evaluation of Nano Zinc (ZnO) for Surface Enhancement of ATR–FTIR Spectra of Butter and Spread

Abstract

The effect of nano zinc (ZnO) particles in surface enhancement of attenuated total reflection–Fourier transform mid-infrared spectroscopy (ATR–FTIR) has been studied in butter and spread. Due to the health implications associated with consumption of trans fats, the studies also included the determination of band corresponding to trans fats of butter/spread in the nano-zinc-treated samples. The FTIR spectra of nano-zinc-treated butter showed enhancement of bands related to (―C―O, ―CH2―) at wave number 1,238 cm−1 and (O―C―C) band of esters at wave number 1,100 cm−1. Shifting in wave number to 1,150 cm−1 and reduction in its peak intensity was observed with the band corresponding to 1,162 cm−1 (―C―O stretch). Reduction in peak intensity of the bands at about 2,915 and 2,850 cm−1 (C―H groups) was also observed. In the case of spread, nano zinc reduced the peak intensities of FTIR bands at 2,915 cm−1, 2,850 cm−1 (―C―H― (CH2) stretches), 1,746 cm−1 (―C═O ester), 1,465 cm−1 (―C―H (CH2, CH3)), 1,375 cm−1 (―C―H (CH3)) and 1,156 cm−1 (C―O, ―CH2). Trans fats band corresponding to ═C―H stretch (trans bonds, 966 cm−1), was observed in pure butter and spread. Trans fatty acids in butter and spread were quantified with the aid of calibration/validation standards using trielaidin and triolein and by using partial least squares regression analysis. However, the band at 966 cm−1 was hindered in Zn-treated butter and reduced in Zn-treated spread.