Development of Physically Modified Hydrocolloids and Starches for Enhanced Salt Perception

Lead Research Organisation: University of Nottingham
Department Name: Sch of Biosciences


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.

Technical Summary

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.

Planned Impact

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.


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Description Overall Objective: To produce a range of ingredients, suitable for thickened foods, by using novel processes for physical modification (particularly by extrusion and steam processing) of hydrocolloids and starches.

The work carried out was divided into a set of four specific objectives.
1. To evaluate processing methods in terms of energy efficiency and use of sustainable materials.
There were two major types of processes used throughout the work.
1.a Thermomechanical extrusion.

The processing method most utilised in the programme was mechanical thermal extrusion whereby materials are subjected to both thermal and mechanical energies. This process is continuous and is considered efficient in terms of capital, energy and effective heating compared to thermal heating alone. Although the particulate format was still best achieved by the xanthan other colloids could be extruded to form strips and if these strips were ground the powders formed all showed modified behaviour compared to the supplied powders.

The studies on the xanthan extruded product have led to a series of findings that include:
a) That the process can be readily scaled for commercialisation
b) Varying the thermomechanical extrusion conditions will cause slight changes in the properties of the particulate material.
c) Originally it was hypothesised that the mechanical shear was the major factor in the creation of new structures. However, within the programme it has been shown that the major contributor to restructuring is the thermal element of the processing regime. Heating the polymer at specific water contents will allow restructuring of the polymer and this creates polymers with novel behaviours. A patent has been applied for this new material.
1.b Steam Injection: The programme looked at direct injection of steam into a fluid stream causing heat shock and high vortex mixing. As part of this programme equipment for direct entrainment of powders into the mixing zone was created and used. Original studies using this equipment concentrated on hygienic preparation of the food materials and the creation of an emulsion mix that could be created as a continuous operation for comparison with an emulsion made as a batch using conventional high shear mixing. The test emulsions and the control were tested for their rheology and sensory perception. This equipment showed that xanthan gums and other hydrocolloids could be added at relatively high concentrations to water to create molecularly dispersed material. A homogenous 5% xanthan solution was made within seconds of its addition to the water stream. This is particularly hard to do for xanthan where specialised equipment and grades of materials as well as long mixing times are often used to create homogenous solutions. Thus this equipment may well be very useful for creation of xanthan thickened samples. Previously work reported that under the unusual mixing, heating and hydration systems that materials exhibit unusual properties could be created; in particular native starch granules could be made to superswell. A range of starches and flours were tested at various temperatures increments and their properties compared with swelling using jet cooking and stirred hydration. The additional moisture, added as steam, made direct comparisons difficult, but there was no clear evidence that superswelling was occurring. However, there was some doubt that the equipment was performing. The excellent mixing properties and the potential for new structure formation still made this technique of great interest and worthy of further investigation.

2. To carry out sensory work to quantify the improvements in salt perception and mouthfeel from the consumer perspective of the new ingredients.

Samples created as a white sauce were compared using the new technologies. There were no differences perceived by the sensory panel in the saltiness.
A key assumption made for some of the work on salt perception was that samples that mixed well would be perceived as being more salty. This had been previously been shown for starches. Samples akin to a low calorie tomato soup were created using particulate xanthan and normal xanthan and as a control a soup thickened with modified starch. The samples were shear viscosity matched at 50 S-1. These samples showed very different dispersion characteristics on mixing. Soups were compared at ambient temperature for flavour intensity by an experienced panel using a paired comparison test and the samples were not perceived as different. These findings are now published.

The results clearly did not show that the samples that readily mixed would have better salt perception. Three concepts were therefore considered and have enhanced the general understanding of salt perception and the impact of xanthan as a thickening agent.

Samples of a dry soup mix, white béchamel type sauce and a beef and barley soup were all prepared commercially using the particulate form of xanthan and their standard material.

3. To relate sensory properties to solution structure, as characterised by a range of methods, particularly rheology, calorimetry and mixing behaviour.

Extensive work was carried out to establish the mixing and rheological behaviour of the materials at different stages of their manufacture and for evaluation of final products. New methods for looking at phase transitions in biopolymers were pioneered in this study.

4. To develop an underpinning scientific understanding of the mechanism by which these new structures are created.

Substantial understanding has be elucidated on how processing creates new structures and how the process can be manipulated to create structures with different properties. It was found that under high specific mechanical energy conditions in the extruder a particulate form of xanthan is produced. The transition from the particulate to the conventional molecular form was thought to be driven by shear forces, but further work has shown the relevance of temperature, often at very local locations, is also of critical importance. This temperature shear environment has then been used to further modify the hydrocolloids. Critical temperatures are salt dependent. A new material that has something of the pasting properties of native starches has been created. In addition a new particular a form of xanthan was produced that gelled irreversibly on heating in the same way as a globular protein. This is the basis of a patent.
Exploitation Route The dynamics of salt release in the mouth and the creation of in vitro tests to predict have be shown to be very pertinent to soups and sauce type product, this requires additional understanding for predictive product formulation.
Two xanthan based materials have been demonstrated to have novel properties and have be shown they can be made on commercial scales. These need exploitation.
The use of flash DSC has been demonstrated as possible for biomaterials. This is relevant across a range of subject areas.
Sectors Agriculture, Food and Drink,Manufacturing, including Industrial Biotechology

Description Exploitation of the particulate form of xanthan: Creation of food quality materials for commercial testing. From the collaboration with Clextral and CP Kelco it was possible to create sufficient particulate xanthan samples that it could be used to create a series of food grade materials. This material has been used with a series of small and larger companies to demonstrate its potential as an easy to use agent for increasing viscosity. In particular a sauce trial was done with an SME as they were experiencing particular problems with the hydration of xanthan for manufacture of the dill and lemon sauce product. Two major international companies are scrutinising the potential of the particulate form of xanthan with a view to commercialisation. Salt release during eating The salt dependent behaviour of the particular form of xanthan will allow low viscosities in salt until a certain temperature has been achieved. This can allow ease of filling and rapid heat transfer into products, whilst achieving a viscous end product with low degradation. This was demonstrated through a side project to the main LINK scheme and further work is now being sponsored by a large company. The use of particulate xanthan has also been looked at by companies wishing to use it as an aid in gluten free products. New form of particulate xanthan: The new form of xanthan has different properties to the original particulate material and can target a different series of required functional behaviours. This material is currently being patented (JA72907P). Once the patent is secure Biopolymer Solutions and the University of Nottingham will seek funding to further understand the mechanism by which the polymer is formed and whether a thermal stable gel can be created once the physically modified polymer is treated. It is expected that funding for this work will be sought from a commercial company and some funding from the TSB smart awards. Steam injection: The easy hydration and the possible creation of new microstructures still seems possible using high pressure steam injection. To this end a project has now been started between Nottingham and an SME that has a prototype machine to allow a tuneable injection of steam into the liquid flow stream. Initial funding of £50k has already been secured from the company for the initial investigations. If the work shows that structures can be created that are novel further assistance and funding will be sought from the appropriate bodies. This project is also expected to be supported through a 1/2 funded studentship available through the EPSRC Centre for Innovative Manufacturing. Funding for training programmes with Brazil will be used to host a postdoctoral fellow for a year and his major area of research will be to look at hydration of hydrocolloids modified through processing. Flash DSC: A highlight of the LINK programme was the use of Flash DSC to see changes in biopolymer not normally observable. On completion of the programme work is continuing and the partnership with Mettler is strong. Results from the equipment are being shown at the Application of Thermal Analysis - Training Day in Manchester, where both Nottingham and Mettler can hear what others experts in the field think of these novel findings. It can be anticipated that further funding will be sought to enable this new and interesting development of thermal methods to be available for food biopolymers.
First Year Of Impact 2013
Sector Agriculture, Food and Drink,Construction,Education,Healthcare,Manufacturing, including Industrial Biotechology
Impact Types Economic

Description Beneficial use of particulate xanthan
Amount £29,100 (GBP)
Funding ID RGS113036 
Organisation Mars Incorporated UK 
Sector Private
Country United Kingdom
Start 03/2014 
End 12/2014
Description Evaluation and development of the HydraMach (CRD device)
Amount £50,429 (GBP)
Funding ID RGS112393 
Organisation Cambridge Research and Development Ltd 
Sector Private
Country United Kingdom
Start 05/2014 
End 12/2014
Description Innovate UK
Amount £561,298 (GBP)
Funding ID 66334-473203 
Organisation Sainsbury's 
Sector Private
Country United Kingdom
Start 02/2017 
End 02/2019
Title Flash DSC use for biopolymer 
Description Use of method developed by consortium member for evaluation of samples associated with the project. First time work published on these samples using this technique 
Type Of Material Improvements to research infrastructure 
Year Produced 2014 
Provided To Others? Yes  
Impact method demonstrated at thermal method group meeting and development of this technique by the equipment suppliers. 
Title Investigations of filament stretching in the presence of saliva 
Description use of specialized rheological techniques to look at biopolymer behaviour in the presence of human saliva. 
Type Of Material Biological samples 
Year Produced 2014 
Provided To Others? Yes  
Impact Demonstration of how behaviour of different polymers may behave in mouth. May help to understand sensory data. 
Description Biopolymer Solutions 
Organisation Biopolymer Solutions
Country United Kingdom 
Sector Private 
PI Contribution Access to a range of companies interested in the small company. A platform to exploit patent on particulate xanthan.
Collaborator Contribution Wide ranging understanding of the processing methods and materials used. Personal links to those involved in the project and outside the consortium who would be interested in the outputs.
Impact papers and a patent further research work and collaborations
Description Clextral SAS 
Organisation Clextral
Country France 
Sector Private 
PI Contribution Increased understanding of the extrusion of hydrocolloids and the associated shear and temperature forces occurring within an extruder.
Collaborator Contribution Supplied key inofrmation for the production of bulk samples of particulate xanthan. Demonstrated that the process can be readily scaled for commercialisation and created 250kg of material for assessment by food companies.
Impact papers
Description Mettler-Toledo 
Organisation Mettler Toledo Safeline Ltd
Country United Kingdom 
Sector Private 
PI Contribution Provision of a greater understanding of the thermo changes occurring in polymers and access to a wide audience interested in using thermal methods
Collaborator Contribution Mettler Toledo, a consortium member, had available a Flash DSC and this equipment can heat very small quantities of materials at very fast rates, so fast that water loss and other such transitions (particularly degradation) can be negated to the extent that other underlying changes can be perceived. As part of their in-kind contribution this machine was made available for the study of changes to biopolymers as a way of predicting restructuring of their microstructure. From this early work and subsequent use of the equipment a paper is forthcoming and talks being given on the use of the DSC and the changes to xanthan which give rise to its particular form and changed behaviour.
Impact Specific conference poster on flash DSC. Paper being written.
Description Pursuit Dynamics 
Organisation Pursuit Dynamics
Country United Kingdom 
Sector Private 
PI Contribution Understanding and proof of principle of the action of steam injection to the emulsification properties of an exemplar food product (an emulsion), understanding the importance of hygienic manufacture, sensory data on samples, data on hydrocolloid hydration and starch swelling after steam injection.
Collaborator Contribution Use and then fitment within the academic department of the steam injection apparatus. Supply of information on previous work.
Impact Data that shows the performance of the equipment across a range of materials of interest to the rest of the consortium.
Description Thermo Fisher 
Organisation Thermo Fisher Scientific
Country United States 
Sector Private 
PI Contribution Opportunities to work with a range of hydrocolloids for extrusion. To have access to scale up equipment.
Collaborator Contribution Better understanding of the equipment based on research scale thermo mechanical extrusion. Assistance with the manufacture of parts for extrusion in the time scale suitable for the project. Training sessions for the changing of screws and other hard ware associated with the extruder.
Impact New equipment parts. Understanding of the hydrocolloids behaviour in the extruder.
Start Year 2008
Description ck kelco members of the consortium 
Organisation CPKelco
Country United States 
Sector Private 
PI Contribution Supplied knowledge of the behaviour and an understanding of the relevant merits of thermal and mechanical structuring of materials relevant to cpKelco. To clarify the influence of the different elements of the processing studies using a capillary rheometer has been carried out as has some technology for static heating, which was originally developed for the bioenergy programme (BB/G01616X/1) on the cpKelco samples.
Collaborator Contribution The materials used for the thermomechnical extrusion programme were mostly supplied by CP Kelco, one of the consortium partners. The polymers extruded included: carboxymethyl cellulose (CMC), carrageenan (Genugel WR-78), high acyl gellan (Kelcogel LT100), low acyl gellan (Kelcogel Kgel), pectin type LM 18 CG-Z, pectin type D low set-Z. All of these were supplied by cpKelco from sustainable sources and were of food grade. This range of polysaccharides was decided on by the whole consortium to help elucidate the mechanism by which the xanthan is physically modified so that it causes the unusual particulate swelling behaviour that formed the basis of the patent shared with the consortium (Biopolymer Solutions).
Impact Joint papers Understanding of the materials
Start Year 2008
Title Modified Colloids 
Description This invention relates to modified colloids, such as xanthan gum. Methods of making modified colloids and products comprising modified colloids. 
IP Reference JA72907P.GBA 
Protection Patent application published
Year Protection Granted 2014
Licensed No
Impact Further development work on the thermal system and exploitation of the materials made via extrusion
Title Creation of a physically modified form of colloid 
Description A physically and thermally treated materials that has unique hydration and gelling characteristics 
Type Of Technology New Material/Compound 
Year Produced 2014 
Impact A commercially exploitable material that preforms to give unique structures under typical food processing conditions. 
Description Reporting to local SME 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Demonstrations and workshops on benefits of the research being undertaken and possible exploitation of the work by the local SMEs

We generated several development projects and work placement opportunities for the students associated with the group
Year(s) Of Engagement Activity 2013,2014