title: Structural characterisation of partially glycosylated whey protein as influenced by pH and heat using surface-enhanced Raman spectroscopy.
abstract: 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.
authors.affiliation: Department of Food Science, University of Minnesota, 1334 Eckles Avenue St. Paul, MN 55108, United States.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.forename: Lili
authors.initials: L
authors.lastname: He
authors.forename: Theodore P
authors.initials: TP
authors.lastname: Labuza
authors.forename: Baraem
authors.initials: B
authors.lastname: Ismail
mesh_terms: D006031:Glycosylation; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D008894:Milk Proteins / Q000737:chemistry*; D055550:Protein Stability; D017433:Protein Structure, Secondary; D013059:Spectrum Analysis, Raman / Q000379:methods*; D000067816:Whey Proteins
chemical_list: D008894:Milk Proteins; D000067816:Whey Proteins