Spatial distribution of protein and phenolic constituents in wheat grain as probed by confocal raman microspectroscopy

Confocal Raman microspectroscopy is an appropriate method to investigate th e microscopic structure of a wheat grain. The technique does not require an y destructive preparation of the sample and is rapidly performed. The high spatial resolution reveals molecular and chemical heterogeneity within cell ular dimensions. Using specific vibration bands as markers, the technique p ermits reconstruction of spectral images. The different components of wheat (Triticum aestivum) were chemically and structurally characterised by Rama n microspectroscopy. The work was focused on the protein content and compos ition of the starchy endosperm and on the composition of the aleurone cells walls in arabinoxylan and ferulic acid derivatives. Particular attention w as given to these components because of their role in cohesion of the starc h-protein matrix interface and of the endosperm-envelope interface. Confoca l Raman microscopy was also used to follow the evolution of protein content and structure during grain development of various wheat varieties selected on the basis of hardness level and aptitude to separation of peripheral la yers during milling. (C) 2000 Academic Press.