In-vitro food mastication has been simulated by incorporating size reduction process, followed by incubation with human saliva. However, they do not suffice to simulate the actual oral breakdown process where disruption by mastication (chewing) and wetting/lubrication by salivation take place simultaneously. In this study, in-vitro oral digestion of rice gels with different amylose contents was simulated by instrumentally performing mastication and salivation. The hardness of artificial saliva-treated rice gels was distinctly lowered with increasing chewing cycles and the rice gels with high amylose contents showed the highest degradation rate. When the rice gels were subjected to non-destructive tomographic analysis, the high amylose rice gels were clearly shown to be favorably fragmented into smaller pieces by chewing, followed by the low and intermediate amylose samples. These results could be explained by their cohesive texture rather than hardness. Therefore, this study may help understanding the changes in the physical properties of cereal-based foods during oral digestion.