Year: 2026
Type: preprint
Abstract: The objective of this work was to establish the peak assignment in liquid state 31P NMR of milk systems and investigate the method as a tool to identify di!erences in casein micelles as consequence of di!erent processing history. Suspensions of milk protein concentrate with removal of casein micelles by EDTA addition and ultra-centrifugation were analyzed by liquid state 31P NMR and compared with the original suspensions. Moreover, 1H-31P total correlation spectroscopy NMR was applied to di!erentiate between peaks from phosphoserines and inorganic phosphate in dairy systems. The results provide direct evidence that the signals observed in liquid-state 31P NMR of milk systems originate from phosphoserine residues in soluble caseins and inorganic phosphate in the serum phase, thereby resolving conflicting assignments reported in previous studies. Furthermore, it is demonstrated that liquid state 31P NMR is able to quantitatively di!erentiate the native amount of inorganic phosphate in the serum phase in suspensions of milk protein concentrate and skim milk. In light of the crucial importance of the calcium phosphate equilibrium between milk serum and casein micelles for understanding the casein micelle structure and its changes, liquid state 31P NMR shows potential as a suitable technique to get a better understanding of how processing a!ect the mineral equilibrium in casein micelles.
Source: ChemRxiv
Institution: Aarhus University
Language: English
Topic: Proteins in Food Systems
Subfield: Food Science
Domain: Life Sciences
Open Access status: green
Award: G369459519
OpenAlex ID: W7214719475