25 New insights to glutenin structure in flour processing.

J. H. SKERRITT and M. P. Lindsay. CSIRO Plant Industry and Quality Wheat CRC Ltd, Canberra, ACT 2601 Australia.

Three microscopic approaches were used to analyze specific associations between subunits within the glutenin macropolymer in doughs. Scanning electron microscopy of doughs prepared from lines null for several HMW- or LMW-glutenin subunits enabled us to visualize changes in the network of protein surrounding starch granules. It revealed that HMW-GS played the primary role in the formation of this network, although deletion of LMW-GS led to the formation of sheets rather than a three-dimensional network. Subsequent experiments were aimed at establishing specific roles for glutenin subunits in the structural organization of the macropolymer. Confocal light microscopy was used to study incorporation behavior of labeled model subunits, with either 0, 1 or 2 cysteine residues on gluten structure in doughs. Immunolocalization transmission electron microscopy at higher magnification revealed that HMW-, LMW- glutenin subunits and gliadins were differentially located within the gluten network of doughs, suggesting that they have distinct roles in the structural organization of gluten. The microscopic and earlier biochemical results have enabled us to better understand protein interactions in doughs and to develop refined models for the structure of the glutenin macropolymer. We will now extend these initial results from flour-water dough systems to the variety of dough formulations used in industry.