Abstract: To address the problem of increased whey separation and insufficient textural quality of reduced-fat yogurt, collagen peptides (CP) and hyaluronic acid (HA) were added to reduced-fat yogurt. In the presence of CP, HAs with different molecular masses was first screened based on whey separation and apparent viscosity. Subsequently, the effects of CP/HA mass ratios on the microstructure, physicochemical properties, rheological and tribological behaviors, antioxidant activity, and sensory quality of reduced-fat yogurt were systematically evaluated. The results showed that compared with HAs with other molecular masses, 95 kDa HA combined with CP provided a more favorable balance between reduced whey separation and acceptable drinking viscosity. Within a CP:HA mass ratio range of 9:1 to 7:3, a denser protein-polysaccharide network was formed, resulting in reduced whey separation and improved lubrication performance and sensory acceptance. Among the tested formulations, the one with a CP:HA mass ratio of 8:2 exhibited the highest system stability and antioxidant activity. Overall, the combined incorporation of CP and 95 kDa HA effectively improves the structural stability and overall quality of reduced-fat yogurt, providing experimental evidence for formulation optimization of low-fat and reduced-fat fermented dairy products.

Key words: reduced-fat yogurt; collagen peptides; hyaluronic acid; physicochemical properties; rheological properties; antioxidant activity