INVESTIGADORES
ALCARAZ Mirta Raquel
congresos y reuniones científicas
Título:
EXTERNAL CAVITY-QUANTUM CASCADE LASER (EC-QCL) SPECTROSCOPY AND CHEMOMETRICS FOR PROTEIN ANALYSIS IN COW'S MILK
Autor/es:
KULIGOWSKI, JULIA; SCHWAIGHOFER, ANDREAS; ALCARAZ, MIRTA R.; VENTO, MÁXIMO; LENDL, BERNHARD
Lugar:
Barcelona
Reunión:
Congreso; Chemometric in Analytical Chemistry; 2016
Resumen:
The determination of total protein content in cow?s milk is a routine application of mid-infrared (IR)transmission spectroscopy. However, the quantitation of protein in this kind of samples demands laboriousand time consuming experimental work. We report an analytical method based on the direct spectroscopicdetermination of casein (Cas), α-lactalbumin (αLA) and β-lactoglobulin (βLG) in cow milk samples. Forspectra acquisition, a custom-made setup equipped with a tunable EC-QCL light source, operated in pulsedmode at room temperature, and a temperature stabilized flow cell with an optical path length of 38 µm wasused. An advanced data processing protocol was applied to compensate for fluctuations in the fine structureof the emission curve that are inherent to the employed light source due to mechanical instabilities [1]. MidIRtransmission spectra of aqueous protein standard mixtures, as well as cow?s milk and spiked cow?s milksamples were acquired in the 1600-1700 cm-1region (amide I band). Science based calibration (SBC)algorithm was employed for compensation of changes in the background signal attributed to the milk matrix.After background correction, partial least squares (PLS) was employed to build regression models for eachof the three proteins by comprising spectra of aqueous calibration standard solutions and backgroundcorrectedmilk samples. Finally, predictions of individual protein concentrations in commercial and spikedcow?s milk were carried out. Protein concentrations determined in commercially available milk samples were24.5±1.4, 1.4±0.9 and 2.4±0.2 mg mL-1for Cas, αLA and βLG, respectively. Recovery values for spikedsamples were ranging between 95±8%, 101±22% and 99±4% for Cas, αLA and βLG, respectively. In lightof the results obtained, this high throughout method has the potential to be employed as a standard tool forquality control of milk, without requiring any sample preparation