Engineering analysis of duodenal digestion

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Latty, Clifford (2019). Engineering analysis of duodenal digestion. University of Birmingham. Ph.D.

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Abstract

There is a strong interconnection that exists between food structure and gut function and finally health. This work sought to perform engineering analysis of the phenomena occurring during food digestion with emphasis in mixing and reactions limited by mass transfer. Specifically, three (3) in vitro models able to perform food digestion were developed. The salient model developed, Dynamic Duodenal Model (DDM) represented the anatomy and physiology of the human duodenum. The models were used to test the influence of viscosity and intestinal motility on dissolution, mixing and mass transfer of nutrients in the small intestine. Model fluids and real foods (novel breads) passed through the models.
High viscosity fluid systems attenuate sugar uptake, likely due to the reduction in the convective effect of mixing, which also slows starch digestion in breads.
Analysis of the hydrodynamics in the DDM were performed using Positron Emission Tomography (PET), to visualise mixing and mass transfer inside the lumen. The in-vivo lumen flow that occur in the human small intestine during mixing were similarly reproduced in the duodenal model and compared. PET images showed that the rate of axial velocities were associated with the type of particulate systems in addition to viscous effects.
Dissolution profiles of bread boluses were visualised by the structure-mechanics digestion model. Image analyses of the structural changes undergone by boluses suggested that food structure and pH were the main factors driving bolus breakdown and dissolution in digestion.
The main outcomes and implication of this research are the following: (I) Identification of selected wheat varieties with specific arabinoxylan fibre traits for bread making that can influence carbohydrate metabolism and hence glycemic index value for bread (II) Segmen- tation motility augment mixing and nutrient delivery to the gut wall boundary by means of changes in mass transfer coefficient (III) Development of systematic model that can describe optimised baked breads (gluten free), to alter digestion, and (IV) Visual method that can describe the breakdown pathways undergone by different chewed bolus particulate systems.
The concluding findings contributed more knowledge on some of the factors controlling the physical processes of digestion as well as the effects of different food formulations on nutrient absorption. This may help to develop new lines of structured healthy foods.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):