Unrevealing the impact of impaired mastication capacity on the kinetics of proteolysis of egg white gel boluses formed using the bio-inspired oral mastication system (iBOMS-III)

Abstract

Understanding how oral mastication influences the digestion of food is essential for designing diets and products suited to populations with varying chewing abilities. In this study, we used an innovative in vitro bionic oral mastication system (iBOMS-III) to replicate different chewing conditions by adjusting mastication force and saliva flow rate. Egg white gel (EWG) was used as a model protein-rich food. Comparative analyses showed that the iBOMS-III operating under standard adult-like conditions (A1B1C: 400 N force, 1.2 mL/min saliva flow) produced EWG boluses with a median particle size of 3.17 mm, closely matching the in vivo median of 3.29 mm. Boluses formed under reduced mastication conditions (A2B2C and A3B3C) had larger particle sizes of 4.16 mm and 4.83 mm, respectively. Subsequent in vitro digestion revealed that the free amino group release after gastric and intestinal phases was significantly higher for A1B1C (1.36 mmol/g protein) and in vivo (1.38 mmol/g protein) boluses compared to A2B2C (1.18 mmol/g) and A3B3C (1.06 mmol/g) (p < 0.05). Rheological analysis confirmed that boluses produced with lower mastication force and saliva flow showed higher hardness and viscoelastic moduli, making them more resistant to enzymatic breakdown. These findings confirm that iBOMS-III can realistically mimic human mastication and quantify its downstream effects on digestion. The findings provide mechanistic evidence that chewing performance directly influences protein digestibility, offering insights for the development of foods tailored to older adults and individuals with impaired oral function.