Effect of simulated digestion in vitro on the rheology and biological activity of Lilium davidii var.unicolor Salisb Polysaccharide

This work explored the digestion of lily polysaccharides at different stages in the human body through simulation experiments, and studied its rheological properties and biological activities. The structural characteristics of the digested lily polysaccharide were confirmed by infrared spectroscopy and the molecular weight after digestion was determined. Through rheological experiments, the viscosity of digested lily polysaccharide decreased in the flow performance test with the increase of shear rate, showing the characteristics of shear thinning. Meanwhile, after Cross model fitting, its correlation was better, which was consistent with the order of area size of thixotropic rings in thixotropy experiments; its dynamics measurement of viscoelasticity showed that the solutions of LPG 7, LPGI 9 and LPI 7 were in a relatively stable solid state and had good gel properties and system stability. And the interrelationships between the molecules were active, which was in line with the optimal pH and reaction conditions for digestion of lily polysaccharides in the human body. The antioxidant activity of lily polysaccharide after digestion was tested, and it was found that lily polysaccharide after digestion had good scavenging activity on DPPH, ABTS free radicals and FRAP. These results provide changes in the structure and activity of lily polysaccharides after digestion, provide a theoretical basis for further understanding of the mechanism of digestion in vivo, and provide valuable and scientific support for future use as functional foods and drugs. Graphical abstract