Development of Physically Modified Hydrocolloids and Starches for Enhanced Salt Perception

An understanding of how food behaves in the body is obviously important. There is a physical dimension to this, in addition to nutritional and biochemical factors. Central to the work proposed in this grant is the idea that foods can mix with saliva and other water based fluids to different levels of efficiency and this impacts on how the food tastes and behaves when eaten. It is has been demonstrated that saltiness is perceived as being higher from starch thickened foods when compared to foods thickened with other materials, even though the viscosity and level of salt are the same. The reason for this is that in the starch system much of the starch remains in a particulate form, while the other materials form solutions that are then hard to mix. In the mouth, sodium that remains in the food and cannot reach the taste receptors on the tongue will not be perceived as salty. Therefore ingredients that can be added to foods that give excellent mixing quality, and hence allow the best perception of flavour, are required. A major part of the project will concentrate on the development of new particulate thickening systems using hydrocolloids and starches (already common ingredients in foods) using physical technologies that use energy sources efficiently and have low wastage. Work at Nottingham partly through a Bridge LINK project, on which this full project is based, has demonstrated the feasibility of developing new particulate ingredients from hydrocolloids such as xanthan gum. Physically modified starch that maintain particulate structures in a similar way to chemically crosslinked starches are already available, but the project will use a new approaches to produce improved ingredients of this type. The project will use a combination of sensory evaluation and instrumental techniques to develop criteria to predict salt perception and mouthfeel. In addition, a limited amount of work will be performed to confirm that the mixing hypothesis is relevant to behaviour in the stomach. To deliver this programme will require a team of companies and academics working together to further develop and then exploit the understanding partly result from a Bridge LINK project. Industrial partners in the team will supply a detailed knowledge of both suitable starting ingredients for the processing technologies and foods that will benefit from new ingredients that would allow salt levels to be reduced whilst maintaining the same flavour. There is also a requirement for expertise and specialist equipment for extrusion processing and thermal analysis, which will be supplied by industry and management from staff that are free of the major teaching and administrative pressures of a successful applied science department. Hence, the programme will have five companies plus an academic partner in a consortium to deliver the work and who can translate the findings into 'better for you' food products without loss of quality.

This project aims at creating a range of new physically modified hydrocolloids and starches that can be used to thicken salt reduced foods. It will also develop a model that relates extensional and shear rheological parameters of thickened foods to mouthfeel and salt perception. It is clear that there is a physical dimension to how food behaves in the body in addition to nutritional and biochemical factors. Central to this proposal is the idea that viscous liquids foods of comparable viscosity mix with body fluids at different levels of efficiency. Salt perception from starch thickened foods is generally better than from hydrocolloid thickened materials at the same shear viscosity, where this viscosity is determined at shear rates appropriate to in mouth conditions. The reason for this difference is that the viscosity in starch thickened products generally arises from swollen particles, whereas in hydrocolloid thickened products viscosity results from macromolecules in solution. It has been shown that the former mix much more efficiently with water (and hence saliva) than the latter. A consequence of this is that for the hydrocolloid thickened systems sodium ions remain entrained within the poorly mixing viscous matrix and are therefore swallowed before reaching the taste sensors. To be of value this understanding needs to be translated into novel food ingredients that can deliver the required rheological properties. Hence this project will concentrate on the following specific areas. a) The development of new particulate thickening systems from both hydrocolloids and starches using technologies that use energy sources efficiently and have low wastage. b) The use of sensory evaluation to demonstrate that these and conventional thickeners give salt perception and mouthfeel that can be predicted on the basis of the mixing / particulate hypothesis c) The development of new rheological criteria to predict salt perception and mouthfeel.

Who benefits: The major beneficiaries from this research will be the general population whereby they could obtain foods with the expected taste attributes, but with lower sodium. Consequent health benefits also assist the nation. The Food Standards agency has targeted soups and sauces as products that need reformulation if the salt targets for the UK are to be met. It is recognised that the UK leads many other nations in its concerns on the usage of sodium in manufactured foods. This project will enable those participating to be in the forefront of salt reduction technology and thus the companies within the consortium and the researchers working on the project will gain a competitive advantage. Specifically, manufactures will be assisted in the development of healthier food. Achievement of the lower salt levels is due to the creation of new food ingredients and this can be a major manufacturing opportunity in its own right. Development of an extrusion processing business for the fabrication of new food ingredients, preferable based in the UK, could have a significant impact. In- line with other major government concerns, this project deals with provision of these new ingredients using production methods that are energy efficient and use renewable food allowed materials that are only physically modified, hence can be considered safe. Collaboration: The consortium is constructed to take advantage of the skills of small expert companies, as well as larger ingredient and food suppliers. This tiered arrangement within the supply chain should allow exploitation of the findings at each level and negate conflict within the consortium. The industrial partners will wish to exploit some of the results of the project in their field of business, hence some information will be confidential. For the success of the project, it is essential that manufacturing plants undertake pilot scale work and development of processes. A collaboration agreement, based on previous Nottingham led LINK programmes will, with minor modification, form the basis of the agreement for ownership and exploitation of the IP arising from the project. This agreement also sets out the responsibilities and rights of the participating members and the mechanisms for disclosure of information outside the consortium. Dissemination: Although the project is targeted at some specific products, knowledge will be gained in both physical chemistry and manufacturing strategies that are generally applicable for aqueous based materials. Hence, learning gained should be generic and could influence many food production scenarios as well as non food applications. The project will utilise some model systems with the full intention that these results are publishable. Members of the Food Science group at Nottingham regularly contribute plenary lectures etc and would expect to validate their knowledge through such talks and published papers. In addition dissemination will be assisted by utilising the East Midland Development Agency, the iNett, the Food Processing Faraday and through positive responses to the sponsoring bodies regarding propagation of non confidential knowledge. Project Management: The project will be run along the lines of similar successful Link programmes run at Nottingham. Prof John Mitchell, who has recently retired from full time work at the University, will use his expertise gained over many Link programmes to co-ordinate this project. In addition to informal meetings there will be a formal meeting of the consortium at the start of the project and at six monthly intervals. On these occasions there will be: a meeting of the financial steering committee, a policy board meeting chaired by an elected industrial member and scientific progress reports given orally and in writing. Dedicated staff employed on the project will also assist companies with their in-kind contributions when necessary to ensure continuity within the project.