Maillard-induced glycosylation of whey protein improves solubility and thermal stability over a wide pH range. However, the relationship between structural changes and functional enhancement upon glycosylation is not well-characterized. Therefore, our objective was to characterise these structural changes and determine the protein conformation at various pH and thermal treatments, using surface-enhanced Raman-spectroscopy. The spectra of glycosylated protein revealed a new peak at 983 cm-1 that can be used as a Raman marker for the early stage glycosylation. Upon glycosylation, structural variations were significant at the disulfide, hydrophobic, amide III, amide II, and amide I regions. Ionisation of carboxyl groups at all tested pH values, and increased β-sheet configuration were also observed. The noted structural modifications imparted molecular rigidity and a consequent resistance to denaturation upon thermal treatment over a wide pH range. These findings can be used to explain various functional enhancements of whey protein upon glycosylation.
Bibliographical noteFunding Information:
This work was supported by funds from the Midwest Dairy Association TM. We would like to acknowledge Thermo Fisher Scientific (Madison, WI) for the use of the DXR Raman microscope.
- Maillard-induced glycosylation
- Structural characterisation
- Surface enhanced Raman spectroscopy (SERS)
- Whey protein