Protein and microstructure evaluation of harder-to-cook and easy-to-cook grains from different kidney bean accessions

Harder-to-cook and easy-to-cook grains from different accessions were compared for protein profiling and starch microstructural characteristics. Harder-to-cook grains had higher accumulation of 27 kDa polypeptides (PP) in some accessions, resulting in their high trypsin inhibitory activity. Harder-to-cook grains showed higher pasting temperature, peak viscosity, final viscosity and setback viscosity than easy-to-cook grains. Damaged starch granules in starch isolated from harder-to-cook grains were observed. Harder-to-cook grains had higher paste stability formed by proteins isolates, which was attributed by the presence of relatively high proportion of β-sheets in them. Harder-to-cook grains had lower proportion of high Mw and higher proportion of low Mw protein fractions than easy-to-cook grains. Easy-to-cook and harder-to-cook grains also differed significantly in size of starch granule. Starch isolated from harder-to-cook grains had lower proportion of small size granules than starch isolated from easy-to-cook grains.