Simultaneous use of transglutaminase and rennet in milk coagulation: Effect of initial milk pH and renneting temperature

The objective of the present study was to assess competitive interactions between transglutaminase (TGase) and rennet during rennet coagulation of skim milk. Rennet coagulation was achieved at two different renneting temperatures (30 °C and 34 °C), three initial milk pH levels (6.5, 6.3 and 6.1) and two TGase concentrations (0.6 U g−1 protein and 1.8 U g−1 protein). Results of the relative caseinomacropeptide in serum and degree of polymerization revealed that TGase influenced both the primary and secondary phases of rennet coagulation, respectively. Overall, the higher the renneting temperature and the lower the TGase level, the lower were the yields of the rennet gels. The coagulation times (tc) of the gels decreased with decreased initial milk pH and increased coagulation temperature. The optimum initial milk pH, coagulation temperature and TGase concentration were determined to be 6.3, 30 °C and 1.8 U g−1 protein.