Rapid quantification of casein in skim milk using Fourier transform infrared spectroscopy, enzymatic perturbation, and multiway partial least squares regression: Monitoring chymosin at work.
In this study, we introduce enzymatic perturbation combined with Fourier transform infrared (FTIR) spectroscopy as a concept for quantifying casein in subcritical heated skim milk using chemometric multiway analysis. Chymosin is a protease that cleaves specifically caseins. As a result of hydrolysis, all casein proteins clot to form a creamy precipitate, and whey proteins remain in the supernatant. We monitored the cheese-clotting reaction in real time using FTIR and analyzed the resulting evolution profiles to establish calibration models using parallel factor analysis and multiway partial least squares regression. Because we observed casein-specific kinetic changes, the retrieved models were independent of the chemical background matrix and were therefore robust against possible covariance effects. We tested the robustness of the models by spiking the milk solutions with whey, calcium, and cream. This method can be used at different stages in the dairy production chain to ensure the quality of the delivered milk. In particular, the cheese-making industry can benefit from such methods to optimize production control.
Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800Kgs. Lyngby, Denmark. Electronic address: aba@kt.dtu.dk.
A
A
Baum
Foss Analytical, Foss Allé 1, DK-3400 Hillerød, Denmark.
P W
PW
Hansen
Foss Analytical, Foss Allé 1, DK-3400 Hillerød, Denmark.
L
L
Nørgaard
Arla Foods amba, Innovation, Rørdrumvej 2, 8220 Brabrand, Denmark.
John
J
Sørensen
Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800Kgs. Lyngby, Denmark.
J D
JD
Mikkelsen
D000818:Animals; D002138:Calibration; D002364:Caseins / Q000032:analysis*; D002611:Cheese / Q000032:analysis; D012085:Chymosin / Q000378:metabolism*; D005504:Food Analysis / Q000295:instrumentation / Q000379:methods*; D006358:Hot Temperature; D006868:Hydrolysis; D007700:Kinetics; D016018:Least-Squares Analysis; D008892:Milk / Q000737:chemistry* / Q000201:enzymology; D017550:Spectroscopy, Fourier Transform Infrared; D000067816:Whey Proteins
D002364:Caseins; D000067816:Whey Proteins; D012085:Chymosin
cheese; infrared spectroscopy; multiway; parallel factor analysis