title: Modified properties of a glycated and cross-linked soy protein isolate by transglutaminase and an oligochitosan of 5 kDa.
abstract: BACKGROUND
  Soy protein is an important protein ingredient for the food industry; however, its properties can be improved by enzymatic and chemical modifications. This study applied a new enzymatic glycation and cross-linking to modify soy protein isolate (SPI), using an oligochitosan of 5 kDa and transglutaminase. Properties of the obtained glycated and cross-linked SPI (GC-SPI) were unknown and thus assessed.
  
  
  RESULTS
  GC-SPI contained glucosamine of 13.6 g kg-1protein, but less reactable &bond;NH2than SPI (0.42 vs. 0.50 mol kg-1protein). Infrared spectra and circular dichroism results showed that GC-SPI other than SPI and cross-linked SPI had more &bond;OH in molecules, and was more disordered in secondary structure. In comparison with SPI, GC-SPI showed enhanced water-binding capacity, could form aggregates with enlarged hydrodynamic radius (180.2 vs. 82.9 nm) and negative zeta-potential (-31.2 vs. -27.7 mV) in dispersion, but exhibited lower thermal stability (e.g. greater mass loss) upon heating at a temperature above 288 °C. GC-SPI also had lower in vitro proteolytic digestibility than SPI due to the protein cross-linking.
  
  
  CONCLUSIONS
  Oligochitosan of 5 kDa and transglutaminase can be used to glycate and cross-link SPI. This approach is applicable to generate potential protein ingredient with good hydration and dispersive stabilisation. © 2016 Society of Chemical Industry.
authors.affiliation: Key Laboratory of Dairy Science, Ministry of Education, Northeast Agricultural University, 150030, Harbin, PR China.
authors.forename: Miao
authors.initials: M
authors.lastname: Fu
authors.affiliation: Key Laboratory of Dairy Science, Ministry of Education, Northeast Agricultural University, 150030, Harbin, PR China.|Synergetic Innovation Center of Food Safety and Nutrition, Northeast Agricultural University, 150030, Harbin, PR China.
authors.forename: Xin-Huai
authors.identifier: http://orcid.org/0000-0001-9682-5426
authors.initials: XH
authors.lastname: Zhao
mesh_terms: D055162:Biocatalysis; D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry; D048271:Chitosan; D003432:Cross-Linking Reagents / Q000737:chemistry*; D005944:Glucosamine / Q000737:chemistry; D006031:Glycosylation; D006358:Hot Temperature; D057927:Hydrophobic and Hydrophilic Interactions; D009844:Oligosaccharides; D055550:Protein Stability; D017433:Protein Structure, Secondary; D012995:Solubility; D030262:Soybean Proteins / Q000737:chemistry*; D011503:Transglutaminases / Q000737:chemistry*
chemical_list: D003432:Cross-Linking Reagents; D009844:Oligosaccharides; D030262:Soybean Proteins; C493484:oligochitosan; D002686:Chitin; D048271:Chitosan; D011503:Transglutaminases; D005944:Glucosamine
keywords: cross-linking; glycation; oligochitosan; property; soy protein isolate; transglutaminase