Chinese rice noodles form the viscoelastic texture by dual high-temperature retrogradation: An insight into the mechanism

Chinese rice noodles, despite being gluten-free, yet exhibit a desirable high viscoelastic texture. The viscoelasticity is primarily attributed to the dual high-temperature retrogradation (HR2) process, but the underlying mechanism remained unclear. To clarify this mechanism, the relationship between the texture-related qualities (cooking, textural, and digestive properties) of noodles and the muti-scale structural changes of starch during the HR2 process were examined. The results revealed that the micromechanical homogeneity and short-range order of the rice noodles were notably increased after HR2, accompanied by the formation of numerous A- and V-type crystals, leading to a relative crystallinity of up to 19.62%. The presence of a high number of A-type crystals caused the rice noodles to form a high-viscosity paste upon cooking. After cooking, the residual heat-resistant Vtype crystals acted as "primary nuclei" for molecular rearrangement, thereby strengthening the gel network structure and resulting in a high viscoelastic texture. As a result of the gel network with exceptional viscoelasticity, the hardness and chewiness of HR2 noodles increased significantly, while the cooking loss and digestibility were remarkably reduced.