Abstract: The effects of adding different amounts of polysaccharides isolated from hawthorn leaves (HLP) on the quality parameters of fermented milk were investigated, including total viable count, water-holding capacity, titratable acidity, color, texture, rheological properties, antioxidant activity and sensory properties. The quality characteristics of fermented milk were measured with a texture analyzer, a rheometer and a color difference meter, and the antioxidant activity was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging method, salicylic acid method and Fe3+ reducing power assay. The results indicated that HLP could stimulate the growth of lactic acid bacteria and acid production during the fermentation process. When HLP was added at 0.12%, the fermented milk had the highest water-holding capacity of 60.24%; at an addition level of 0.16%, the fermented milk had the highest hardness, viscosity and chewiness. Simultaneously, the maximum DPPH and hydroxyl radical scavenging rate and Fe3+ reducing ability of fermented milk with added HLP were 80.7%, 81.6% and 0.56, respectively. These were significantly higher than those of the blank control group (P < 0.05). The addition of a certain amount of HLP can effectively improve the quality and antioxidant capacity of fermented milk. This study provides a theoretical basis and technical support for the application of hawthorn leaf polysaccharides.

Key words: hawthorn leaf polysaccharide, fermented milk, quality, antioxidant activity