Dynamic Digestion Models: General Introduction

Abstract

The fi rst section of this chapter has focused on static digestion models and their specifi c applications. Whilst these static models have many advantages, they mainly function to mimic the biochemical processes in the gastrointestinal (GI) tract and usually use a single set of initial conditions (pH, concentration of enzymes, bile salts, etc.) for each part of the GI tract. However, this simplistic approach is often not a realistic simulation of the more complex in vivo conditions, where the biochemical environment encountered is constantly changing and physical parameters such as shear and grinding forces can have a large impact on the breakdown of larger food particles and the release of nutrients. Several dynamic digestion models have been developed in recent years to address these complex aspects of digestions, and four of these dynamic models will be presented in more detail in the following subchapters. This introduction will provide a brief overview of how the aspects of geometry, biochemistry and physical forces have been addressed in these and other dynamic digestion models. Keywords Dynamic model • Digestion • GI tract • In vitro GeometryThe human gastrointestinal tract consists of distinct compartments of differing shapes, sizes and orientations. These need to be considered when designing a realistic dynamic model. The stomach has a shape of an expanded J, with food entering from the esophageal sphincter at the top and eventually being released through the pylorus at the bottom. During digestion, body position may have an infl uence on some aspects of gastric digestion, especially gastric sieving of larger particles and pharmaceuticals. Three main approaches have been followed in the design of the models' gastric compartments, each with their own advantages and disadvantages: vertical alignment, horizontal alignment and beaker.

Structural breakdown of starch‐based foods during gastric digestion and its link to glycemic response: In vivo and in vitro considerations

“…As static digestion models cannot sufficiently mimic the physical breakdown of food, dynamic gastric digestion models have been developed to simulate the mechanical disintegration of solid food and allow for the dynamics of gastric mixing. Dynamic gastric models typically consist of a synthetic gastric compartment with moving components that simulate mechanical disintegration of food (Thuenemann, 2015). There are many types of in vitro dynamic gastric digestion models to simulate the human stomach, such as the dynamic gastric model (Vardakou et al., 2011), human gastric simulator (Ferrua & Singh, 2015; Kong & Singh, 2010), and the TNO Gastro‐Intestinal Model (TIM) advanced gastric compartment (Bellmann et al., 2016).…”

Meta‐Analysis for Correlating Structure of Bioactive Peptides in Foods of Animal Origin with Regard to Effect and Stability

“…Static models differ in several important aspects: type and concentration of enzyme used, number of steps and time of particular phase of digestion, rate of stirring, and other parameters (Hur, Lim, Decker, & McClements, ). Dynamic models include division into subcompartments, mimicking different structures and functionalities in the gastrointestinal tract, and account for physical forces and changes in kinetics during digestion (Thuenemann, ).…”

Emerging technologies and their impact on regulatory science

“…Flow dynamic simulators mimicking the gastrointestinal tract are highly reliable for microbial-chemical interaction studies, but they typically lack human cells, although this can be overcome by introducing mucin-covered microcosms in the reactors. [200][201][202][203][204][205][206] An example of a flow dynamic simulator is the BFBL simulator developed in Spain which includes a small intestine and three reactors simulating the ascending, transversal, and descendant large intestine. Stabilization of composition and metabolism of fecal microbiota takes place over 14 days, after which the system is fed with the compound under study.…”