Enclosed cues in food bolus physical properties responsible for swallowing

International audiencePurpose: The major goal of mastication is to transform food in a bolus suitable for swallowing by size reduction and saliva lubrication of food fragments. This purpose must be achieved for safe swal- lowing. Nevertheless, the description of the bolus properties has never really been made. Methods: Twenty young normo-dentate adults were instructed to chew samples of test food and to spit out the resulting boluses at different moments corresponding to fractions of the complete masti- catory sequence. The bolus collected just before swallowing was also analysed. Rheological characterization of boluses was realized using a compressive test. Different parameters were extracted from the stress–strain curves. Particle size distribution in the boluses was analyzed by sieving. Results: Rheological properties of boluses were found to regularly evolve in the course of mastication. From the beginning of the sequence to the swallowable bolus, a decrease in hardness and an increase in cohesiveness, springiness, and adhesiveness were observed. Important changes in rheological properties of the food bolus appeared just before swallowing. A rapid decrease in particle size was observed at the beginning of the masticatory sequence fol- lowed by a more progressive change. Conclusion: This work described the temporal evolution of the physical properties of the bolus during chewing. This description Enclosed cues in food bolus physical properties responsible for swallowin