Quality attributes of the set-style yoghurt from whole bovine milk as affected by an enzymatic oxidative cross-linking

The impact of an enzymatic oxidative cross-linking of milk proteins on quality attributes of set-style yoghurt was investigated in the present study. Whole bovine milk was pretreated by a ternary system comprising horseradish peroxidase, glucose oxidase and glucose at 4 degrees C for 48 h and fermented by a commercial direct vat set starter after table sugar addition and pasteurization. The measured bacterial count in the treated milk was less than 2 x 10(3) CFU/mL. Electrophoresis results revealed that both the treated milk and the treated yoghurt contained protein polymers about 11%. The treated yoghurt had the same main composition as the control yoghurt, but higher apparent viscosity, elastic and viscous moduli, larger thixotropic loops area (3.19 vs. 1.97 Unit) and lower syneresis (21.0% vs. 33.8%). Texture profile and microstructure analysis showed that the treated yoghurt had higher hardness (106.6 vs. 92.0 g) or adhesiveness (450 vs. 367 g s), and finer network structure.