Structural characterisation of partially glycosylated whey protein as influenced by pH and heat using surface-enhanced Raman spectroscopy

Qian Wang, Lili He, Theodore P. Labuza, Baraem Ismail

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)313-319
Number of pages7
JournalFood Chemistry
Volume139
Issue number1-4
DOIs
StatePublished - Aug 15 2013

Bibliographical note

Funding 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.

Keywords

  • Maillard-induced glycosylation
  • Structural characterisation
  • Surface enhanced Raman spectroscopy (SERS)
  • Whey protein

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