Deformation index (GDI) in grain as a criterion for wheat gluten quality

Abstract

The nutritional benefits of wheat bread largely depend on quality and content of the most valuable part of the grain, its protein complex, namely elastic, and quite extensible gluten. In recent years, there has been a tendency for deterioration of grain quality indicators, namely the indicator ‘gluten quality’ regulated by GOST. There are often the circumstances, when gluten acquires properties of increased viscosity and bran particles are firmly held by gluten proteins. In this case, it is practically impossible to extract it and it is characterized by the term ‘non-extractable’. At the same time, gluten extracted from flour (in the absence of bran) of the same grain sample corresponds to the 1-st and 2-nd classes of quality. Thus, in the first variant, the producers face losses as the grain of the 5th class is non-food, and in the other, we get good grain when gluten is extracted out of flour. The breeders of the research institutions face the similar dilemma when selecting breeding material according to gluten quality. Both different ways of extracting gluten often give opposite effect for the same genotype. The purpose of the current study was to assess the conformity degree of GDI, identified according to GOST according to such indicators as GDI in flour, sedimentation, rheological properties on a mixograph. In order to estimate if wheat is strong, valuable and weak, there is not enough only elastic ity, which is identified using the GDI device (gluten deformation index). The deformation index after extracting gluten is not always an objective result of its quality, therefore, there is a need in additional study, e.g. determination of the gluten deformation index (GDI) in flour, SDS sedimentation, rheological properties of the dough on a mixograph, which characterize gluten ‘strength’ (elasticity, strength, etc.). These methods will allow researchers to estimate the quality of breeding material more efficiently, and agricultural producers will have a comprehensive description of gluten quality of grown grain.