Researchers in the Division carry out extensive work on polysaccharides. The two research groups most closely involved are the National Centre for Macromolecular Hydrodynamics led by Professor Stephen Harding and the Food Structure Group led by Professor Sandra Hill . The work in the Division covers the whole water content range (dilute solutions to dry materials) and extends beyond food applications to therapeutics and drug delivery. Expertise and interest include:-
Molecular size of polysaccharides in dilute solution can be determined by a combination of ultracentrifugation, measurement of intrinsic viscosity, gel permeation chromatography and field flow fractionation. The latter two techniques use multi angle laser light scattering to obtain an absolute value of molecular size of the fractionated material.
Gelation of polysaccharides is followed by a combination of dynamic rheology and microcalorimetry. The textural properties of the gel is evaluated by texture analysis. An area of current interest is the relationship between gel texture and flavour release during food consumption.
There is extensive work on starch. Changes to starch during processing during baking of bread, heat processing to prepare breakfast cereals and extrusion processing to produce snack foods remain of major interest. Such processes are often considered in terms of the starch state diagram. Viscosity and mobility depend on the distance from the glass transition line and loss of order and recrytstallisation/retrogradation by the position relative to both the glass transition and melting lines. The state of starch in the product is evaluated by a wide range of techniques including Rapid Viscosity Analysis, calorimetry, microscopy, X-ray diffraction and ultracentrifugation.
The mechanical properties of polysaccharide films at low water contents can be related to both structural and mobility parameters. There has been an interest in fracture properties of films not only because of its relationship to the perceived crispness of a food product but also because of its importance for the use of polysaccharides to replace synthetic polymer in applications such as packaging. The University of Nottingham is the only UK partner in the European Polysaccharide Network of Excellence (www.epnoe.org/) which focuses on polysaccharide material science.
Pharmaceutical applications of polysaccharides is investigated through collaboration with the School of Pharmaceutical Sciences and colleagues elsewhere. For example there is major interest in chitosan because of its bioadhesive properties.
The journal Carbohydrate Polymers and the company Biopolymer Solutions Ltd were both founded in the Division.