Effect of Ultrasonic Posttreatment on Physicochemical, Structural, and Rheological Properties of Stearic Acid‐Modified Khesari Pea Starch

Abstract

This research aims to evaluate the effects of varying stearic acid (SA) concentrations (2%, 4%, and 6%), followed by an ultrasound treatment with SA, on the morphology, structure, functionality, and rheological behavior of starch extracted from khesari peas. The ultrasonically treated samples showed higher complexing index (CI) values (23.65%–92.86%) than starch‐SA complexes, decreased amylose content (30.22%–18.11%), and increased water‐holding capacity (175.18%–306.65%). FTIR spectra suggested the formation of starch‐SA complexes, indicated by additional peaks at 2849 and 1704 cm − 1 , along with a new band near 684 cm − 1 in SA‐treated samples, absent in native starch. Ultrasonically treated samples retained characteristic bands but showed reduced peak intensities, implying structural degradation. Rheological analysis revealed a viscosity reduction in samples with higher SA levels. Ultrasonicated samples displayed non‐Newtonian flow behavior, with shear stress and shear rate showing a nonlinear relationship, especially at low shear rates. In summary, this study highlights the novelty of sequential SA complexation and ultrasonication in tailoring the functional, structural, and rheological characteristics of khesari pea starch, offering a potential approach to developing starch ingredients for food packaging, nutritional, and pharmaceutical applications.