144 Interrelationships of large and insoluble glutenins measured by different methods.

E. M. MAGNUS (1), Å. Longva (1), A. K. Uhlen (2), E. M. Færgestad (1), and S. Sahlström (1). (1) MATFORSK, The Norwegian Food Research Institute, Osloveien 1, N-1430 Ås, Norway; (2) Agricultural University of Norway, Dept. of Crop and Horticulture Sciences, P.O. Box 5022, N-1432 Ås, Norway.

The mixing and breadmaking properties of wheat flours have in many studies been shown to be related to the presence of specific subunits of glutenin, as well as to the size of the polymeric glutenins. Various analyses for prediction of the breadmaking quality of wheats are based on quantitative measurements of these large and insoluble glutenins. Determination of the content of glutenin macropolymer, the content of insoluble polymeric glutenin and the proportion of the highest molecular weight glutenin obtained by sonication in phosphate-buffer containing sodium dodecyl-sulfate (SDS) and size-exclusion chromatography are commonly used for this purpose. The objective of this work was to compare the results obtained by these different methods for quantification of the least soluble glutenins and their relationships to the mixing properties of the flours. The study also involved further examination of the proteins extracted by the different analytical procedures. Preliminary results indicated that the proportion of the highest molecular weight glutenins extracted by sonication prior to separation by size-exclusion chromatography was positively correlated with the content of insoluble polymeric glutenins. Both these parameters were positively correlated with mixograph parameters and SDS sedimentation volumes.