Gluten proteins from spelt (Triticum aestivum ssp. spelta) cultivars: A rheological and size-exclusion high-performance liquid chromatography study

The aim of this study was to understand the chemistry of spelt (Triticum aestivum ssp. spelta) gluten in relation to its quality, to classify European spelt cultivars based on gluten quality, and to compare their protein compositions with those of modern wheats. Gluten quality of two sets of 25 spelt cultivars was studied using dynamic oscillatory and creep tests, an SDS sedimentation test, moisture content of the wet gluten and wet gluten content. These data were compared with the results of size-exclusion HPLC analyses of the spelt proteins. Significant correlations indicated that insoluble polymeric proteins (IPP) contributed resistance to deformation in creep tests, elasticity in oscillatory and creep tests, and swelling capacity of the gluten. Gliadins had the opposite effects, whereas the contribution of soluble polymeric proteins (SPP) depended on the type of test. In creep tests (strain 0.3–1.5) SPP behaved similarly to gliadins, in oscillation (strain 0.001) they tended to increase elasticity. In comparison to hard red winter wheats, spelt was characterized by lower IPP, but higher gliadins and SPP, resulting in softer and less elastic glutens. A wide variation in gluten quality was found among the spelts. Three groups could be identified by cluster analysis (one closer to modern wheat, a second typical spelt group and a third a poor quality group).