Research on Structural–Mechanical Property of Rice Starch Gels for Food 3D Printing and Flexible Sensing

Starch materials have been widely used in fields of flexible sensing and food 3D printing; rice starch (new source) needs in-depth research for related applications. In this research, a mixing-temperature controlling-cold drying preparation scheme for rice starch gel with stable performance is proposed. In order to in-depth analyze the rice starch internal structural–mechanical behavior, a developed texture analyzer with in situ observation is self-established; the gel internal structure, mechanical behavior, and loading capacity are in-depth analyzed. Effects of rice starch kind (indica, japonica, glutinous) and starch concentration are investigated on internal structure evolution and mechanical behavior. Experimental results show the starch gel is of crosslink network internal structure with pores. The starch dry gel compression force–displacement curve exhibits an S-shaped relation. It can be divided into three stages: elastic deformation, micro-cracking, and overall fracture, matching with rice dry gel internal structure evolution. Rice dry gel peak bearing force order is glutinous starch > indica starch > japonica starch, negatively correlated with internal network structure pore size. The dry gel internal pore size turns out to be small with increasing rice starch concentration. Based on rice starch dry gel mechanical and micro-structure analysis, rice starch gels exhibit optimal structure for application.