On modelling the chemo-mechanical coupled response of starch hydrogel during human gastric digestion
File(s)
Author(s)
Liao, Zisheng
Type
Thesis
Abstract
Glucose homeostasis is essential for human survival, yet is frequently disrupted by hyperglycaemia, which is closely associated with non-communicable metabolic disease such as obesity and type-2 diabetes. A key dietary contributor to hyperglycaemia is the widespread consumption of highly processed starch-based foods with high glycaemic index values. Industrial processing disrupts food structure and alters mechanical properties, making these foods rapidly broken down in the gastrointestinal tract, increasing enzyme accessibility, and accelerating gastric emptying and intestinal glucose absorption.
Therefore, the importance of understanding and engineering the chemo-mechanical properties of starch-based systems for controlled digestion is emphasised. Among starch-based foods, starch hydrogels provide a biocompatible and tunable system for nutritional design and drug delivery. However, their digestion involves coupled enzymatic hydrolysis, mechanical degradation, and large deformation, which is still not fully understood.
To bridge this gap, this thesis combines in vitro experimentation with in silico modelling. Starch hydrogels prepared under different processing conditions were characterised by microscopy, thermal analysis, and extensive mechanical tests, revealing constitutive behaviour governed by the polymer network formed during gelatinisation and retrogradation. Compression tests after enzymatic hydrolysis were employed to characterise mechanical property changes due to degradation, and diffusion tests were conducted to quantify the enzyme transport properties. The experimental result provides the basis for model development and calibration.
A chemo-mechanical constitutive model was proposed to capture hyperelasticity, time-dependent viscoelasticity, retrogradation-induced pseudoelasticity, and enzymatic degradation. Implemented in the Finite Element Method, the model successfully reproduced the coupled diffusion-reaction-deformation behaviour observed experimentally. The framework was extended using the Coupled Eulerian-Lagrangian method to simulate gastric digestion under peristalsis and fluid-solid interactions, and the results were compared with dynamic in vitro digestion tests.
Overall, this thesis establishes a unified experimental-computational approach for quantifying and predicting starch hydrogel digestion, providing an intuitive and quantitative tool for nutritional and biomedical applications.
Therefore, the importance of understanding and engineering the chemo-mechanical properties of starch-based systems for controlled digestion is emphasised. Among starch-based foods, starch hydrogels provide a biocompatible and tunable system for nutritional design and drug delivery. However, their digestion involves coupled enzymatic hydrolysis, mechanical degradation, and large deformation, which is still not fully understood.
To bridge this gap, this thesis combines in vitro experimentation with in silico modelling. Starch hydrogels prepared under different processing conditions were characterised by microscopy, thermal analysis, and extensive mechanical tests, revealing constitutive behaviour governed by the polymer network formed during gelatinisation and retrogradation. Compression tests after enzymatic hydrolysis were employed to characterise mechanical property changes due to degradation, and diffusion tests were conducted to quantify the enzyme transport properties. The experimental result provides the basis for model development and calibration.
A chemo-mechanical constitutive model was proposed to capture hyperelasticity, time-dependent viscoelasticity, retrogradation-induced pseudoelasticity, and enzymatic degradation. Implemented in the Finite Element Method, the model successfully reproduced the coupled diffusion-reaction-deformation behaviour observed experimentally. The framework was extended using the Coupled Eulerian-Lagrangian method to simulate gastric digestion under peristalsis and fluid-solid interactions, and the results were compared with dynamic in vitro digestion tests.
Overall, this thesis establishes a unified experimental-computational approach for quantifying and predicting starch hydrogel digestion, providing an intuitive and quantitative tool for nutritional and biomedical applications.
Version
Open Access
Date Issued
2025-12-02
Date Awarded
2026-03-01
Copyright Statement
Attribution-NonCommercial 4.0 International Licence (CC BY-NC)
License URL
Advisor
Charalambides, Maria
Publisher Department
Department of Mechanical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)