Artificial saliva-induced structural breakdown of rice flour gels under simulated chewing conditions.

Rice flour gels with different amylose contents were subjected to instrumental compression cycles under artificial saliva-spraying conditions to simulate oral mastication and their structural breakdowns were evaluated in terms of rheological and tomographic characteristics. Both mechanical disruption of the gel structure by successive compressions and enzymatic degradation by artificial saliva featured in the simulated chewing process. Highly linear correlations (R > 0.95) were observed in the log plots of peak chewing force and time. The rice flour gels containing higher levels of amylose required high forces to be deformed by compression. Micro-CT analysis demonstrated that the rice flour gels with a weak cohesive texture were fragmented into smaller pieces by chewing, consequently providing channels for artificial saliva to penetrate inside the gel samples. The cohesive nature of foods appeared thus to play an important role in their disruption rate during chewing, probably influencing the masticatory performance with salvia and subsequent swallowing.