Award details

Copy of Self structuring foods with slow burn for control of satiety

Reference	BB/G005478/1
Principal Investigator / Supervisor	Professor Ian Norton
Co-Investigators / Co-Supervisors	Professor Phillip Cox
Institution	University of Birmingham
Department	Chemical Engineering
Funding type	Research
Value (£)	340,262
Status	Completed
Type	Research Grant
Start date	01/01/2009
End date	12/05/2012
Duration	40 months

Abstract

The project is to construct foods (components) that are sensitive to environmental change and will self structure in the stomach. The gel strength and rate of gelation need to be controlled to gel the majority of the stomach contents and then de-assemble over a period of hours to allow stomach emptying to occur over 5 to 6 hours. The acidity of the stomach will be used as the major trigger for self assembly of a number of polysaccharides (eg alginate, pectin, gellan) and proteins (milk, vegetable). These hydrocolloids are families of molecules and the fine structure of the polysacarides will be selected from different sources or manipulated (eg by enzymes) to give increased or decreased acid sensitivity and manipulate the rates of gelation and the final properties. Combinations of these hydrocolloids will be used to control gelation and gel properties by modifying the phase sense and the phase volumes in the de-mixed systems. In order to make these materials compatible with soft foods and to stabilise them for storage and use we will investigate routes for production of fluid gels based on these self structuring systems ie investigate the use of calcium stabilised alginate fluid gels that are additionally capable of acid gelation so that the fluid gel breaks in the stomach and the released hydrocolloid then forms a bulk acid gel. Having developed ways to gel stomach contents and slow empting process we will encapsulate starch in different formats; crystalline, partially hydrated grains or dispersions, into hydrocolloid shells, emulsion droplets or intact plant cells, so that starch digestion is stopped in the mouth and starch has to be digested in the stomach. The encapsulate will be carefully selected to modulate the rate at which digestion occurs so as to release calories over the time period between meals. We will then investigate ways to produce the self structuring and slow burn components at pilot scale and incorporate them in a demonstrator food.

Summary

There is a need to control energy intake of consumers. A problem is that foods have become softer and more easily digestible and are less satiating. This leads to the individual feeling hungry more quickly and wanting to eat again often between meals. It has to be recognised that the consumer however, wants to have foods that are convenient, good tasting and easily prepared. The technical need is therefore to find ways to structure the food so that it is stable during storage and distribution is convenient and tastes good but then is slowly digested resulting in calories being released over hours. One potential way of achieving this is to produce foods that respond to the environment they find themselves in. So a food that is structured with a hydrocolloid that is sensitive to pH and is designed to structure the contents of the stomach (e.g. forms a gel that occupies the whole stomach) is potentially capable of slowing the stomach emptying process. Initial work has shown that this is possible and that the onset of hunger can be delayed by several hours. We intend to extend these initial findings and produce and investigate a range of alginates to control the gelation rate and gel properties under conditions; acidity, salt, temperature corresponding to the stomach. Having developed an understanding of the fine structure control of alginate we will study alternative materials that are acid sensitive (eg pectin, gellan etc) as well as investigating mixtures of these materials with each other and non acid sensitive hydrocolloids for specific kinetic and rheological control. There is a requirement to have temperature and time stable structures so that they can be transported and used in cooked products so we will investigate the use of sheared gels. A significant challenge will be to have materials included that will modulate the energy delivery and slowly release calories after the meal (slow burn) and still be organoleptically acceptable to the consumer. In orderto do this we will include starch in different states; which are known to be digested at different rates and so delivers energy to the body over different timescales from minutes to hours. Starch which is highly crystalline can result in sandy or gritty textures in the mouth, particularly as the retrogradation process is not controlled in the manufacturing process. This has in the past limit the applicability of controlling energy release in soft foods using retrograded/resistant starch. We will investigate ways of including starch in other biopolymer and sheared biopolymer systems including 'hydrocolloid shells'. The shell will be designed to protect the starch against the amylase in the mouth and slow down the acid action in the stomach. This may well require a double or even triple shell to be produced with different hydrocolloids making up the shells. The overall dimensions of the particles will be less than ten microns to avoid oral detection. In addition, starch in plants is more slowly digested than raw starch and we will investigate the separation and inclusion of cellular materials that are texturally and orally acceptable. Having investigated routes to obtain self assembling structures and the way to include and modulate breakdown to control calorie release, we will then use our engineering skills to find ways to produce these materials at scale. As we do so we will be aware of potential problems of use in storage and transportation i.e. breakdown of the structures at elevated temperatures or self structuring occurring on storage before the product is used by the consumer. We will develop cyclised hydrocolloid networks, fluid gels (ie calcium cross linked alginate) which are temperature and time stable but dissolve at acid pH's and restructure into acid gels in the stomach. Fluid gels will be constructed by gelling the hydrocolloids or mixed hydrocolloids under well controlled flow fields and temperature profiles eg temperature ramped turbulent flow.

Committee	Closed Committee - Agri-food (AF)
Research Topics	Diet and Health, Technology and Methods Development
Research Priority	X – Research Priority information not available
Research Initiative	Diet and Health Research Industry Club (DRINC) [2008-2014]
Funding Scheme	X – not Funded via a specific Funding Scheme

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