Quality attributes of the set-style skimmed yoghurt containing enzymatic cross-linked or thermal polymerized whey protein isolate

Impacts of replacing of milk proteins with two modified whey protein isolates (WPIs) on quality of set-style skimmed yoghurt were assessed. WPI dispersion (35 g protein/kg) was cross-linked by transglutaminase for 5–10 min or polymerized at 90°C or 100°C for 10–30 min, mixed with skimmed milk (35 g protein/kg) at 1:2 (v/v), and fermented by a commercial starter at 42°C for 5 h. Compared with the control yoghurt generated from skimmed milk only, these yoghurt samples showed no difference in main chemical compositions, but using the cross-linked WPI somewhat delayed yoghurt fermentation. These yoghurt samples had enhanced values of hardness, adhesiveness, springiness, and cohesiveness but decreased syneresis, especially using long-time and high-temperature treatment for WPI. The cross-linked and polymerized WPIs both conferred yoghurt samples with enhanced viscosity, elastic and viscous moduli, and finer microstructure. In general, the polymerized WPI was better than the cross-linked WPI to enhance these quality attributes