This tutorial will emphasize studies of cellulose crystallinity in higher plants and products derived from them, areas where crystallinity studies are complicated by the small size of the crystalline domain, commonly only a few nanometers transverse to the fiber axis. While the goal of any crystallinity measurement/calculation is to determine the mass fraction of ‘crystalline’ cellulose, both the reason for making the measurement and the physical/biological basis of the chosen technique may vary. We will begin with an overview of different methods for measuring cellulose crystallinity including diffraction, NMR, and other methods. What are the physical bases of each approach, are they in fact measuring the same thing? Or, is this an example of the classic blind men and the elephant problem, where the answer is dependent upon the limited subset of data available to each observer?<br/>     Next, is the issue of what one hopes to gain from the study? Is the goal to provide a marker for accessibility to enzyme action, or to provide batch to batch comparisons in a processing environment? Choices like these influence the relative importance of accuracy vs. precision in selection of methods of measurement and analysis.<br/>     Finally, one needs to consider the kinds of samples that they are going to study. Native plant tissue is likely to have numerous impurities such as lignin, hemicelluloses, silicates and other inorganics, possibly cutins and xyloglucans.  The relative abundance of these will change in any purification process, and that may significantly alter the scattering profile of non-cellulosic material and therefore crystallinity measurements based upon diffraction. The small size of samples required for most techniques raises questions of how representative a sample is of the material from which it was obtained. If addressing all of this sounds like a very tall order, well it is, but we shall try.<br/>

Quantitating cellulose crystallinity: Approaches, problems, and perspectives

253rd National Meeting (2017)

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