Physicochemical, Rheological Properties, and In-Vitro Starch Digestibility of Flours and Starches from Pigeon Pea, Cowpea, Pinto Bean, and Navy Bean

The physicochemical, rheological properties, and digestibility of flours and starches from pigeon pea, cowpea, pinto bean, and navy bean are investigated. Pinto bean flour (PBF) and Pinto bean starch (PBS) show the highest water absorption capacity (WAC), while cowpea flour (CPF) and cowpea starch (CPS) show the highest oil absorption capacity (OAC)- than other pulse flour or starches. All pulse flours show higher solubility than all pulse starches. However, the swelling power (SP) of all flours is lower than starches and SP is comparatively different among starches. Paste clarity, and relative crystallinity (RC), are higher in all flours compared to starches. However, pasting properties and consistency index (K) are lower in flour compared to starches. All the flours and starches exhibit CA-type crystallinity.The Scanning Electron Microscrographs reveals smooth granular surfaces of all starch and flour. Both flours and starches show flow behavior (n < 1) and viscosity decreased with increasing shear rate indicating the non-Newtonian fluid behavior. All starches show higher rapidly digestible starch (RDS) and resistant starch (RS) content but lower slowly digestible starch (SDS) content than all flours. These flours and starches can be used as valuable ingredients for formulating functional food, soup, and starch gel.