title: Influence of milk protein cross-linking by transglutaminase on the rennet coagulation time and the gel properties.
abstract: BACKGROUND
  Transglutaminase (TGase) modifies milk proteins by cross-linking of caseins, with increased cheese yield being the main technological benefit. In the present work the influence of TGase addition in different concentrations (0, 1, 2 and 3 U g(-1) protein in the system) and under different incubation conditions (0 h, 40 °C/2 h, 25 °C/4 h and 5 °C/16 h) on the rennet coagulation time (RCT) and the comprehensive rennet gel properties were investigated.
  
  
  RESULTS
  Modification of milk proteins by TGase in a concentration-dependent manner caused longer RCT and lower gel firmness. The highest TGase concentration and incubation at 40 °C for 2 h resulted in the longest RCT and the lowest gel firmness. Rennet gels obtained from TGase modified milk were characterised by significantly lower values of texture parameters, lower syneresis and were composed of smaller casein micelles, thinner chains and smaller clusters than those obtained from the control milk. The content of whey proteins in the gel from modified milk was higher and the content of individual casein fractions in the milk samples and rennet gels decreased upon TGase modification.
  
  
  CONCLUSIONS
  Rennet cheese with modified textural and nutritional properties and improved yield can be obtained upon TGase modification but simultaneous addition of rennet and TGase is recommended. © 2015 Society of Chemical Industry.
authors.affiliation: Department of Animal Products Technology, Faculty of Food Technology, University of Agriculture in Krakow, Balicka 122, 30-149, Krakow, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Domagała
authors.affiliation: Department of Animal Products Technology, Faculty of Food Technology, University of Agriculture in Krakow, Balicka 122, 30-149, Krakow, Poland.
authors.forename: Dorota
authors.identifier: http://orcid.org/0000-0003-4207-4457
authors.initials: D
authors.lastname: Najgebauer-Lejko
authors.affiliation: Department of Animal Products Technology, Faculty of Food Technology, University of Agriculture in Krakow, Balicka 122, 30-149, Krakow, Poland.
authors.forename: Ilona
authors.initials: I
authors.lastname: Wieteska-Śliwa
authors.affiliation: Department of Animal Products Technology, Faculty of Food Technology, University of Agriculture in Krakow, Balicka 122, 30-149, Krakow, Poland.
authors.forename: Marek
authors.initials: M
authors.lastname: Sady
authors.affiliation: Department of Animal Products Technology, Faculty of Food Technology, University of Agriculture in Krakow, Balicka 122, 30-149, Krakow, Poland.
authors.forename: Monika
authors.initials: M
authors.lastname: Wszołek
authors.affiliation: Department of Animal Products Technology, Faculty of Food Technology, University of Agriculture in Krakow, Balicka 122, 30-149, Krakow, Poland.
authors.forename: Genowefa
authors.initials: G
authors.lastname: Bonczar
authors.affiliation: Department of Animal Products Technology, Faculty of Food Technology, University of Agriculture in Krakow, Balicka 122, 30-149, Krakow, Poland.
authors.forename: Magda
authors.initials: M
authors.lastname: Filipczak-Fiutak
mesh_terms: D000818:Animals; D002364:Caseins / Q000737:chemistry; D002611:Cheese; D012085:Chymosin / Q000737:chemistry*; D005782:Gels; D008892:Milk / Q000737:chemistry*; D011503:Transglutaminases / Q000737:chemistry*; D000067816:Whey Proteins / Q000737:chemistry
chemical_list: D002364:Caseins; D005782:Gels; D000067816:Whey Proteins; C025350:rennet; D011503:Transglutaminases; D012085:Chymosin
keywords: microstructure; milk; rennet coagulation; texture; transglutaminase