NEW METHODS FOR THE STRUCTURAL AND COMPOSITIONAL ANALYSIS OF CELL-WALLS FOR QUALITY DETERMINATIONS

During the past few years several developments have taken place that may have a marked effect on the way we analyze fibrous materials. Near infrared reflectance spectroscopy (NIRS) has become an official method for the analysis of acid detergent fibre and crude protein. New mathematical data treatments such as principal component analysis and partial least squares have made NIRS analysis more robust. Fourier self-deconvolution techniques have been helpful in interpreting NIR spectra of agricultural commodities. Micro-imaging by nuclear magnetic resonance spectroscopy (NMR) allows us to image compounds in the plant, acquire spectra and determine composition. Combining the techniques of NIRS, mid-IR, and solid state NMR has permitted us to understand better the process of ruminant digestion of forages and to determine when and from which sites within the plant components are removed. Because of the use of NIRS it is now possible to obtain an independent measure by more than one means and get a measure of the accuracy of the empirical procedures we have used for many years. As NIRS is a non-consumptive technique, the same sample can be analyzed twice. Previously, only precision of analysis could be determined. Microspectrophotometry in the UV, visible (VIS), NIR, and mid-IR region will allow us to obtain the spectrum of a compound in a cell wall and image that compound. Further, an assessment of the concentration of components can be made on individual cell walls. These techniques, coupled with improved laboratory methods for the determination of fibre and moisture, and their effect on the measurement of quality and the utilization of forages are discussed.