Unaided efficient transglutaminase cross-linking of whey proteins strongly impacts the formation and structure of protein alginate particles

Mikkel Madsen, Sanaullah Khan, Sonja Kunstmann, Finn L. Aachmann, Richard Ipsen, Peter Westh, Cecilia Emanuelsson, Birte Svensson*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

There is a dogma within whey protein modification, which dictates the necessity of pretreatment to enzymatic cross-linking of β-lactoglobulin (β-Lg). Here microbial transglutaminase (MTG) cross-linked whey proteins and β-Lg effectively in 50 mM NaHCO3, pH 8.5, without pretreatment. Cross-linked β-Lg spanned 18 to >240 kDa, where 6 of 9 glutamines reacted with 8 of 15 lysines. The initial isopeptide bond formation caused loss of β-Lg native structure with t1/2 = 3 h, while the polymerization occurred with t1/2 = 10 h. Further, cross-linking effects on protein carbohydrate interaction have been overlooked, leaving a gap in understanding of these complex food matrices. Complexation with alginate showed that β-Lg cross-linking decreased onset of particle formation, hydrodynamic diameter, stoichiometry (β-Lg/alginate) and dissociation constant. The complexation was favored at higher temperatures (40 °C), suggesting that hydrophobic interactions were important. Thus, β-Lg was cross-linked without pretreatment and the resulting polymers gave rise to altered complexation with alginate.
Original languageEnglish
Article number100137
JournalFood Chemistry: Molecular Sciences
Volume5
Number of pages11
ISSN2666-5662
DOIs
Publication statusPublished - 2022

Keywords

  • LC-MS/MS cross-link identification
  • Size exclusion chromatography
  • Dynamic light scattering
  • Far- and near-UV CD
  • Intristic and ANS fluorescence spectra
  • Molecular dynamics inter-residue distance analysis

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