Designing functional foods by understanding food digestion

Bread is a major part of the UK diet; the market is worth almost £2.9 billion, over 9 million loves of bread are sold each day and white bread forms the majority (71%) of bread sold. Foods with a low glycaemic index (GI) have been shown to be protective against type 2 diabetes and CVD. Avoiding frequent elevated blood glucose is thought to reduce the oxidative stress and inflammation which can promote CVD whilst the hyper-insulinaemia that usually accompanies consumption of high GI foods has a proinflammatory effect which may play a role in decreasing insulin sensitivity. However, white bread has a GI similar to glucose itself. As a consequence of its widespread UK consumption any reduction in white bread GI could have significant health benefits. Brown bread has a much higher fibre content that gives health advantages, but forms only a minority of the bread sold in the UK.

Altering nutrient uptake by modifying food formulation to change the viscosity of food digesta is widely accepted. For example, adding guar gum and certain dietary fibres to increase digesta viscosity can significantly delay absorption and transit time of glucose. The reasons for this are however not known, Food manufacturers can thus to an extent control post prandial glucose levels by modifying the viscosity of the digesta. A common approach is supplementing foods such as bread with soluble fibre fractions from other cereals but this affects palatability. Furthermore the role of dietary fiber in modifying digesta viscosity is itself unclear, as the broad nature of FAO/WHO Codex Alimentarius Commission does not discriminate between resistant starches, soluble and insoluble non-starch polysaccharides that might originate from plant cell wall materials, despite the fact they may have widely differing physicochemical properties.

In this work we are aiming to develop a multiscale model to gain understanding of microstructure behavior in the small intestine.

Digestion is a genuinely multiscale problem involving phenomena occurring from cm to nm. The student will work towards obtaining an understanding of relative significance of the transport mechanisms occuring at different scales, especially for oil soluble components. Emphasis will be given in developing a quantitative understanding the effect on transport through the mucus layer and the link with reactions/convective transfer occurring in the bulk of the lumen. Simulation and experimental methods will be used to study interactions among the different length scales involved and identify controlling rate limiting steps for transport which can be used to identify mechanisms.

The work is expected to be in collaboration with Dr. A. Mackie of the Institute of Food Research and will involve using a range of experimental and modeling techniques.

For any additional information please contact Prof. S. Bakalis ([Email Address Removed])