External cavity-quantum cascade laser (EC-QCL) spectroscopy for protein analysis in bovine milk

The analytical determination of bovine milk proteins is important in food and non-food industrial applications and yet, rather labour-intensive wet-chemical, low-throughput methods have been employed since decades. This work proposes the use of external cavity-quantum cascade laser (EC-QCL) spectroscopy for the simultaneous quantification of the most abundant bovine milk proteins and the total protein content based on the chemical information contained in mid-infrared (IR) spectral features of the amide I band. Mid-IR spectra of protein standard mixtures were used for building partial least squares (PLS) regression models. Protein concentrations in commercial bovine milk samples were calculated after chemometric compensation of the matrix contribution employing science-based calibration (SBC) without sample pre-processing. The use of EC-QCL spectroscopy together with advanced multivariate data analysis allowed the determination of casein, α-lactalbumin, β-lactoglobulin and total protein content within several minutes. Fil: Kuligowski, Julia. Health Research Institute La Fe; España. Vienna University of Technology; Austria Fil: Schwaighofer, Andreas. Vienna University of Technology; Austria Fil: Alcaraz, Mirta Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; Argentina Fil: Quintás, Guillermo. Leitat Technological Center; España. Health Research Institute La Fe; España Fil: Mayer, Helmut. University of Natural Resources and Life Science; Austria Fil: Vento, Máximo. Health Research Institute La Fe; España. University & Polytechnic Hospital La Fe; España Fil: Lendl, Bernhard. Vienna University of Technology; Austria