289 Characterization of gluten proteins using flow field flow fractionation and multi angle laser light scattering.

A. A. TSIAMI and J. D. Schofield. Department of Food Science and Technology, The University of Reading, Reading RG6 6AP, UK.

Gluten was extracted with dilute acetic acid from defatted cvs. Riband (weak), Hereward (medium- strong) and Aubaine (extra-strong) and separated into six fractions by salt precipitation. Flow Field Flow fractionation was used to fractionate the glutenin polymers and gliadin further into relatively monodisperse bands and their molecular weights (MW) were determined by Multi Angle Laser Light Scattering in tandem with UV and RI detection. This system enabled us to measure the absolute MW of the gluten fractions and it was possible to determine the weight fraction of each band in the injected sample. The largest glutenin polymers from cv. Aubaine had the highest MWs (1 × 10(^9)) of all cultivars, followed by Hereward (9 × 10(^7)) and Riband (2 × 10(^7)). Glutenin fractions of lower MW were monodisperse with similar sizes in Hereward (8 × 10(^4)) and Riband (6 × 10(^4)). The analogous glutenin fraction of Aubaine cv. had two bands, one with the same MW as the other cvs. (6 × 10(^4)) and the second with higher MW polymers (3 × 10(^6)). No inter-cultivar differences were observed in the gliadin fraction (4 × 10(^4)). There was a good correlation between the MW distribution of glutenin polymers and their rheological properties. Inter-cultivar differences in the rheological behaviour of the total gluten can be attributed to the MW distribution of the glutenin polymers.