Isolation of Dictyophora indusiata polysaccharide and its effects on the multi-structure characteristics and in vitro digestion of extruded rice starch

This paper described the structure changes that occur in rice starch when extruded with a polysaccharide from Dictyophora indusiata (PDI) at different concentrations (0%, 1%, 2%, and 3%, w/w), their interactions, and the in vitro digestion. The mannose, glucuronic acid, galacturonic acid, glucose, and galactose were found in PDI with the content of 30.20%, 1.66%, 0.62%, 62.50%, and 5.03%, respectively. Fourier transform infrared spectroscopy showed that PDI contains pyranose rings. PDI could cause the starch chains to rearrange to generate a more ordered aggregate structures (such as short-order structure, helix structure, or crystalline structure). After adding PDI, the consistency coefficient (K), viscosity, and storage/loss modulus (G'/G") of the starch-PDI complex increased. Finally, PDI addition markedly inhibited the activity of the starch digesting enzyme, thereby increasing the slowly digested components/resistant components (SDC/RC), while reducing the rapidly digested components (RDC). Overall, this study demonstrated that the relationship between the digestibility and structure of rice starch-PDI complex and provided an insight for application of PDI in rice starch-based food products.