Direct determination of casein, α-lactalbumin and
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Direct determination of casein , α - lactalbumin and β - lactoglobulin in cow ´ s milk using an external - cavity quantum cascade laser and chemometric data analysis The authors acknowledge the Austrian Research Promotion Agency (FFG) within the K-project imPACts (contract no. 843546) for funding. JK acknowledges a Sara Borrell grant (CD12/00667) from Instituto Carlos III (Spanish Ministry of Economy and Competitiveness). OBJECTIVE CONCLUSIONS & OUTLOOK 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 laborious and time consuming experimental work. We report an analytical method based on the direct spectroscopic determination of casein (Cas), α-lactalbumin (αLA) and β-lactoglobulin (βLG) in cow milk samples. 1. An EC-QCL setup was applied for the determination of Cas, ɑLA and βLG. 2. The present method supports the direct analysis of samples without sample processing. 3. Background correction employing science based calibration (SBC) is used for compensation of the milk matrix. 4. Quantification of proteins in off the shelf cow milk samples was carried out using PLS regression. 5. This high throughout method could potentially be employed as a standard tool for quality control of milk. Experimental set-up Noise Reduction REFERENCES 1. M.R. Alcaráz, A. Schwaighofer, C. Kristament, G. Ramer, M. Brandstetter, H. Goicoechea, B. Lendl, Anal Chem, 87, 6980-6987 (2015). Grating angle determines emission wavelength EC-QCL Spectroscopy Temp. stabilized (Peltier- cooled) • No sample preparation • Sample volume: 1 ml • Acquisition time: 10 min • Reference spectrum: H 2 O Bernhard Lendl* 1 , Andreas Schwaighofer 1 , Mirta R. Alcaraz 1,2 and Julia Kuligowski 1,3 1 Technische Universität Wien, Chemical Technologies and Analytics, 1060 Vienna, Austria 2 Universidad Nacional del Litoral-CONICET, 3000 Santa Fe, Argentina 3 Neonatal Research Unit, Health Research Institute La Fe, 46026 Valencia, Spain Email: [email protected] EC-QCL Single beam spectra Data treatment routine based on Correlation Optimized Warping (COW), which utilizes inherent mode-hop structures for scan-to-scan alignment, as well as Fourier filtering is applied. Noise reduction by COW and FFT Small fluctuations in the single beam spectra lead to considerable noise in the corresponding absorbance spectrum IR spectra of proteins Quantitative Analysis Casein (Cas) Protein concentrations determined in commercially available milk samples by multivariate calibration (partial least square PLS), were 24.5±1.4, 1.4±0.9 and 2.4±0.2 mg mL -1 for Cas, αLA and βLG, respectively. Recovery values for spiked samples were ranging between 95±8%, 101±22% and 99±4% for Cas, αLA and βLG, respectively Protein structure The amide bond α-lactalbumin (α-La) β-lactoglobulin (β-LG) Conc.:2.5—20 mg/ml 4000 3500 3000 2500 2000 1500 1000 0,00 0,05 0,10 0,15 0,20 0,25 0,30 Absorbance Wavenumber [1/cm] „Amide I“ band Secondary structure information IR spectrum of water (H 2 O)
Transcript of Direct determination of casein, α-lactalbumin and
Direct determination of casein, α-lactalbumin and β-lactoglobulin in cow´s milk using an external-cavity quantum
cascade laser and chemometric data analysis
The authors acknowledge the Austrian Research Promotion Agency (FFG) within the K-project imPACts (contract no. 843546) for funding. JK acknowledges a Sara Borrell grant (CD12/00667) from Instituto Carlos III (Spanish Ministry of Economy and Competitiveness).
OBJECTIVE
CONCLUSIONS & OUTLOOK
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 laborious and time consuming experimental work. We report an analytical method
based on the direct spectroscopic determination of casein (Cas), α-lactalbumin (αLA) and β-lactoglobulin (βLG) in cow milk samples.
1. An EC-QCL setup was applied for the determination of Cas, ɑLA and βLG.
2. The present method supports the direct analysis of samples without sample processing.
3. Background correction employing science based calibration (SBC) is used for compensation of the milk matrix.
4. Quantification of proteins in off the shelf cow milk samples was carried out using PLS regression.
5. This high throughout method could potentially be employed as a standard tool for quality control of milk.
Experimental set-up Noise Reduction
REFERENCES
1. M.R. Alcaráz, A. Schwaighofer, C. Kristament, G. Ramer, M. Brandstetter, H. Goicoechea, B. Lendl, Anal Chem, 87, 6980-6987 (2015).
Grating angledetermines
emissionwavelength
EC-QCL Spectroscopy
Temp. stabilized
(Peltier-cooled)
• No sample preparation
• Sample volume: 1 ml
• Acquisition time: 10 min
• Reference spectrum: H2O
Bernhard Lendl*1, Andreas Schwaighofer 1, Mirta R. Alcaraz1,2 and Julia Kuligowski 1,3
1 Technische Universität Wien, Chemical Technologies and Analytics, 1060 Vienna, Austria2 Universidad Nacional del Litoral-CONICET, 3000 Santa Fe, Argentina
3Neonatal Research Unit, Health Research Institute La Fe, 46026 Valencia, Spain
Email: [email protected]
EC-QCL Single beam spectra
Data treatment routine based on
Correlation Optimized Warping (COW), which
utilizes inherent mode-hop structures for
scan-to-scan alignment, as well as Fourier
filtering is applied.
Noise reduction by COW and FFT
Small fluctuations in the single beam spectra
lead to considerable noise in the corresponding
absorbance spectrum
IR spectra of proteins Quantitative AnalysisCasein (Cas)
Protein concentrations determined in commercially available milk samples by multivariate
calibration (partial least square PLS), were 24.5±1.4, 1.4±0.9 and 2.4±0.2 mg mL-1 for Cas, αLAand βLG, respectively. Recovery values for spiked samples were ranging between 95±8%,
101±22% and 99±4% for Cas, αLA and βLG, respectively
Protein structure The amide bond α-lactalbumin (α-La)
β-lactoglobulin (β-LG) Conc.:2.5—20 mg/ml
4000 3500 3000 2500 2000 1500 1000
0,00
0,05
0,10
0,15
0,20
0,25
0,30
Abso
rbance
Wavenumber [1/cm]
„Amide I“ band
Secondary structure information
IR spectrum of water (H2O)
