Studies on rheological behavior of native and octenyl succinic anhydride modified buckwheat (Fagopyrum esculentum) starch gel and improved flow properties thereof

The effect of octenyl succinic anhydride (OSA) esterification (1%-3% of dry starch) on powder flowability, functionality, pasting, and gel rheological properties of buckwheat starch (BS) was examined. The physical and flow properties like bulk density, tapped density, Hausner's ratio, Carr's index, cohesion index, and caking strength of starch improved significantly after esterification, indicating better flow behavior and storage stability. The solubility and swelling power were significantly increased, leading to a significant increase in peak viscosity and breakdown, while pasting temperature, setback, and final viscosity decreased. The esterification also restricted the retrogradation, which appeared as a lower hardness of retrograded gel. Starch gel prepared at 5%, 10%, and 15% concentrations showed shear thinning behavior. The dynamic shear properties obtained within the linear viscoelastic region showed weak gel behavior with a more elastic nature and were also demonstrated by the Power law. Practical application The OSA modifies the structure and surface of starch granules to change the physical properties which help in better powder flowability of the dried starch. The findings on powder flowability of BS may help powder manufacturers to control and design powder handling and transportation equipment by preparing non-cohesive, non-sticky, and flowable dried starch powder. The findings of the rheological characteristics of BS gels can be exploited in the preparation and optimization of soup premix, thickening agents, food additives, and gravies. Moreover, the OSA modified gel has a low retrogradation rate, which could be used in a product like bread and cakes.