343 Microstructural study of Triticum aestivum wheat grain by confocal Raman microscopy.

O. PIOT (1), J. C. Autran (2), and M. Manfait (2). (1) Laboratoire de Spectroscopie Biomoléculaire, UFR de Pharmacie, 51 rue Cognacq Jay, 51096 Reims cedex, France; (2) Unité de Technologie des Céréales, INRA, 34060 Montpellier, France.

To date, little is known of how wheat grains fracture and of the molecular species that are involved in the milling process. A better understanding of the molecular basis of the grain cohesion can lead to an optimisation of the milling by selecting more interesting varieties or by applying specific treatment on commonly raised wheat. The cohesion of the kernel grain depends on a protein content located at the interstices of starch granules. The separation between the kernel and the envelope depends on the composition of the aleurone cell walls in ferulic acid and polysaccharide chains. Raman microspectroscopy is a very well appropriate technique to characterise the molecules responsible of the grain cohesion, since it is non-destructive and can be readily applied in-situ. The high spatial resolution permits, per example, to differentiate between two different components such as protein and starch granule within the grain kernel. Confocal Raman microscopy has been performed on grains sections (50 µm thick) of various Triticum aestivum samples supplied by INRA and Champagne Céréales. Raman spectra recorded at different parts of such sections are very specific. The technique permits to identify the components of starchy endosperm and of the aleurone cells layer. It permits also to correlate the wheat grain hardness with the content and the structure of the starchy endosperm protein. It is also used to study the effect of chemical treatment on the binding of the constituents of the aleurone cell walls. In addition, certain marker bands have been used to construct spectral images.