Vibrational spectroscopy for milk fat quantification: line shape analysis of the Raman and infrared spectra

This paper presents a systematic analysis of the infrared absorption spectra and Raman scattering of the triacylglycerol molecule predominant in raw bovine milk. Gas chromatography measurements were also performed and revealed the palmitic, stearic, and oleic acids as the most predominant fatty acids in the composition of milk. Based on the gas chromatography results, infrared, and Raman spectra of the triacylglycerol with this combination of fatty acids were simulated. The theoretical spectra were compared with the experimental ones of milk fat and fluid raw milk. Assignment of bands of milk fat was proposed, which can be used for a quality monitoring of the product. We also performed a multivariate model of partial least squares from samples of fluid milk with different concentrations of fat. As a result, the most important variables in the projection were selected as vibrational markers for quality monitoring and quantifying of this important constituent of milk. Copyright © 2016 John Wiley & Sons, Ltd. This paper presents a systematic analysis of the infrared absorption spectra and Raman scattering of triacylglycerol molecule, predominantly found in raw bovine milk. Infrared and Raman spectra of the triacylglycerol were calculated and compared with the experimental measurements of milk fat and raw milk. In the discussion, the assignments for bands of milk fat were proposed and a model to determine the milk fat content was developed.