Project Details:
Critically evaluated techniques for size separation characterization of starch
| Project No.: | 2007-058-1-400 |
| Start date: | 2008-03-05 |
| End date: | |
| Division: | Polymer Division |
To produce a reliable means of characterize starch by size separation techniques (such as size exclusion chromatography and field-flow fractionation), by critically examining and reconciling the various, and presently rather diverse, methodologies developed independently by leading groups in the field.
Improvements in human and animal nutritional needs, and industrial applications such as paper manufacture, require structure-property relations for starch. Characterising the structure is complex because one of the two types of starch in grains, amylopectin, is hyperbranched and of very high molecular weight. Size separation techniques (size-exclusion chromatography, field-flow fractionation), with multiple detection, provide in principle powerful tools for obtaining data which are sensitive to this complex structure. However, reliable application of these methods is bedevilled by two problems: (1) not all the starch may be dissolved, and (2) shear scission may occur during separation. Recognizing these problems, several leading researchers in the field over the last few years have independently devised various protocols, typically involving the use of solvents (eluents) such as dimethyl sulfoxide of varying degrees of dryness, with or without other additives such as dimethylacetamide and LiBr, various dissolution regimens, and various flow techniques. However, there has been no comparison of the data obtained from different set-ups. This project will bring together these leading groups to discuss the full technical details of their different procedures, including the reasons for these being chosen by the particular group, and perceived problems with these various methods. A round-robin will then be organised to characterise the same sample by the varying techniques. The results will be used to develop improved techniques which can be used by researchers world-wide to obtain reliable and reproducible results.
- project announcement published in Chem. Int. July 2008
Jan 2010 - The first of three publications, as set out in the project is entitled 'Reliable measurements of the size distributions of starch molecules in solution: current dilemmas and recommendations.' MJ Gidley, I Hanashiro, NM Hani, SE Hill, A Huber, J-L Jane,Q Liu, GA Morris, A Rolland-Sabaté, A Striegel, RG Gilbert. Carbohydrate Polymers 79, 255-61 (2010) (doi:10.1016/j.carbpol.2009.07.056)
Jan 2010 - The second publication is Characterizing the size and molecular weight distribution of starch: why it is important and why it is hard. RG Gilbert, MJ Gidley, S Hill, P Kilz, A Rolland-Sabaté, D G Stevenson, RA Cave. Cereal Foods World, 55 139-143 (2010) (doi:10.1094/CFW-55-3-0139)
Next, a round-robin test will be implemented. This will involve three agreed materials available to all participants: a commercial processed starch as available from chemical suppliers, plus two cereal grains, wheat and rice. The tests will include inter-laboratory comparison of dissolution procedures, and of both raw and processed data obtained with different separation modes, set-ups and data-processing packages. This will lead to recommended procedures to enable laboratories throughout the world to obtain reliable size distributions of undegraded whole starch, for subsequent use in establishing the relations between biosynthesis, processing, structure and properties.
In this project, only one-dimensional separation techniques are considered. Size characterisation by methods which do not employ physical separation (such as light scattering on an unseparated sample) are also not considered here. In addressing these problems, the work of the present IUPAC project is complementary to, but not overlapping with, that of an IUPAC project entitled “Terminology and measurement techniques of starch components” (project 2004-022-3-400).
last modified 20110308