title: Caseinate-gelatin and caseinate-hydrolyzed gelatin composites formed via transglutaminase: chemical and functional properties.
abstract: BACKGROUND
  Treatment of food proteins by enzymatic crosslinking and other reactions can confer modified properties on the treated proteins. Bovine gelatin and hydrolyzed bovine gelatin were used to generate two caseinate-based composites via transglutaminase, and potential useful properties to food processing were investigated for both composites.
  
  
  RESULTS
  Caseinate-gelatin and caseinate-hydrolyzed gelatin composites contained 33.4 and 10.3 g kg(-1) protein of 4-hydroxyproline, respectively. Caseinate conjugation with gelatin and hydrolyzed gelatin resulted in two composites with stronger absorption at five wavenumbers during Fourier transform-infrared analysis, demonstrating that they were rich in hydroxyl and carboxyl groups. Both composites exhibited higher viscosity values in aqueous dispersions, lower thermal stability (i.e. higher mass loss) during thermogravimetric analysis and worse emulsifying properties than original caseinate, owing to conjugation and crosslinking via transglutaminase. However, confocal laser scanning microscopy (CLSM) analysis revealed that both composites actually had better emulsion stability after 2 weeks of storage.
  
  
  CONCLUSIONS
  The composites generated were different in chemical characteristics and better in viscosity and emulsion stability than original caseinate. They might have potential as protein thickeners and emulsifiers. CLSM is a better technique to assess emulsion stability of food proteins than the classic turbidity method.
authors.affiliation: Key Laboratory of Dairy Science, Ministry of Education, Northeast Agricultural University, 150030 Harbin, People's Republic of China.|Synergetic Innovation Center of Food Safety and Nutrition, Northeast Agricultural University, 150030 Harbin, People's Republic of China.
authors.forename: Zhen-Ling
authors.initials: ZL
authors.lastname: Luo
authors.affiliation: Key Laboratory of Dairy Science, Ministry of Education, Northeast Agricultural University, 150030 Harbin, People's Republic of China.|Synergetic Innovation Center of Food Safety and Nutrition, Northeast Agricultural University, 150030 Harbin, People's Republic of China.|Department of Food Science, Northeast Agricultural University, 150030 Harbin, People's Republic of China.
authors.forename: Xin-Huai
authors.initials: XH
authors.lastname: Zhao
mesh_terms: D000818:Animals; D002364:Caseins / Q000737:chemistry*; D002417:Cattle; D045703:Emulsifying Agents / Q000737:chemistry*; D004655:Emulsions; D005511:Food Handling; D005780:Gelatin / Q000737:chemistry*; D006801:Humans; D006868:Hydrolysis; D006909:Hydroxyproline / Q000032:analysis; D018613:Microscopy, Confocal; D011503:Transglutaminases / Q000378:metabolism*; D014783:Viscosity
chemical_list: D002364:Caseins; D045703:Emulsifying Agents; D004655:Emulsions; D005780:Gelatin; D011503:Transglutaminases; D006909:Hydroxyproline
keywords: bovine gelatin; caseinate; chemical properties; composite; functional properties; transglutaminase