Development of in vitro oral processing model for different rice: Effects of saliva volume and chewing time on physicochemical properties of rice boluses

The in vitro model is widely preferred for digestion research due to its simplicity, reproducibility, and ethical advantages. However, the differences between in vivo and in vitro digestion present challenges. This study first developed an in vitro oral processing system to explore the influence of saliva volume and chewing time on the physicochemical properties of japonica rice (JR), indica rice (IR), and waxy rice (WR). The results revealed that both saliva volume and chewing time significantly influenced properties like texture, particle size, starch hydrolysis, protein distribution, and microstructure, with chewing time exerting a greater impact. Starch hydrolysis was closely linked to particle size, with fragmentation being the primary factor. An artificial neural network (ANN) model was used to effectively correlate the in vitro simulation conditions with physiological characteristics. By integrating in vivo data, optimized simulation conditions were determined for each rice type: JR-saliva 197.85 ± 21.42 mg/g, chewing 21.02 ± 1.51 s; IR-saliva 198.64 ± 22.41 mg/g, chewing 22.36 ± 0.45 s; WR-saliva 127.11 ± 21.63 mg/g, chewing 14.74 ± 0.90 s.