Acid Hydrolysis‐Induced Nanoconversion of Sweet Potato (Ipomoea Batatas) Starch: Effect on Morphological, Rheological, and Thermal Properties

Abstract

AbstractThe present study aims to prepare starch nanocrystals (SNCs) from sweet potato tuber starch and study their morphological, crystalline, rheological, and thermal properties. The platelet‐like SNCs are obtained using acid hydrolysis of round or polygonal native sweet potato starch granules. The average hydrodynamic diameter of SNCs is 184 nm as measured using the dynamic light scattering technique. The polydispersity index value based upon molecular weight distribution as determined using gel permeation chromatography increases from 1.386 for native starch (NS) to 2.958 for SNCs, indicating the heterogenous molecular weight distribution of acid hydrolyzed starch. The zero value of the radius of gyration for nanocrystals indicates the formation of anisotropic platelet‐like SNCs. The gelatinization temperature and melting enthalpy significantly increased after the nanoconversion of starch granules; thus, SNC's thermal properties are improved after acid hydrolysis of NS. The SNCs exhibit shear‐thinning behavior (lower viscosity) at high concentrations; the visco‐elastic behavior of SNCs dispersions is frequency‐dependent, with elastic character prevalence over viscous at lower frequencies.