Modelling of physical and chemical processes in the small intestine.
Special Symposium - Innovations in Food Technology (LMC Congress)
Flexible Production, PAT & Modelling (Food-3a)
Keywords: food design, in-vitro models, CFD, small intestine
The chemical and physical processing of food in the small intestine is an important step for the digestion and absorption of food. This work is an investigation into the mixing mechanisms induced by physiological intestinal contractions. By mimicking intestinal flow profiles it is possible to carry out sensitivity analysis on the system to determine the effect of changing food formulation parameters and aid the design of novel foods.
The objective of the work was to develop models of the small intestine with which food formulations could be investigated. So far the key developments that have been made are:
The development of a diffusion cell model that allows for the study into the way that different formulations affect molecular diffusion properties. An overhead rheometer has been added to this that allows for apparent shear rates to be determined during the mixing of formulations, while measuring the diffusion rate across a membrane.
A bench top model representing a section of the small intestine has been developed that can reproduce the segmentation motility action found in the small intestine. The small intestinal model (SIM) consists of an inner tube made from a membrane through which the molecule of interest can diffuse, and an outer tube that is impermeable to water. Both tubes are flexible and allow for deformation to take place. As the molecules of interest diffuse through the inner tube membrane into the fluid contained in the outer tube they are detected by analytical instrumentation.
The segmentation motility action of the small intestine is an annular contraction that moves inwards, radial to the centre. This action is responsible for the mixing of the intestinal contents and surface renewal. The action is reproduced for experimental purposes by the inflation and deflation of a rubber cuff that is wrapped around the whole tube.
A computational fluid dynamics (CFD) model using the Fluent software has been developed. The segmentation action of the small intestine is modelled using a deforming mesh.
The diffusion cell has been used to investigate the effect of guar gum on diffusion and convection of small nutrient molecules. The results showed that for a 1% guar solution there was a reduction of 68% in the overall mass transfer coefficient of riboflavin compared to without guar. It has been shown that this reduction in the overall mass transfer coefficient is not due to binding of the molecule to the biopolymer or the fouling of the membrane. Experiments using the SIM have shown the effect of the segmentation motion on the nutrient mass transfer coefficient across the membrane for solutions containing different amounts of guar gum.
So far it has been shown that the reduction in postprandial hyperglycaemia as a result of presence of guar gum can be attributed in part to the reduction in diffusion coefficient seen in static diffusion cell experiments. It has also been shown using the SIM that convection influences the concentration on the inner surface of the membrane. The influence that segmentation has on the overall mass transfer coefficient is reduced as the viscosity is increased.
Further work will be investigating the influence of mixing on enzyme-substrate interactions and how the guar gum affects this under physiological process conditions. Also work on the mixing effectiveness of the segmentation action will be undertaken using flow visualisation techniques.
* Corresponding author: A.Tharakan (axt398@bham.ac.uk)
See the full pdf manuscript of the abstract.
Presented Wednesday 19, 15:20 to 15:35, in session Flexible Production, PAT & Modelling (Food-3a).
