Characterization of hydroxypropylated cassava and potato starches: Functional and physicotechnical properties

Abstract

Introduction: Starch modification is achieved using physical and chemical means to improve the physicochemical characteristics and stability of the molecule with potential applications in specialized drug delivery systems. Purpose: This study aimed to characterize cassava and potato starches modified via hydroxypropylation. Methods: Native cassava and potato starches were subjected to initial pre-gelatinization before being hydroxypropylated (HP) using propylene oxide. The native and HP-starch powders were characterized for their physicochemical properties, powder properties as well as high-resolution analyses using differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Results: Organoleptic evaluations indicated that native starches were white and smooth while HP-starches were off-white, coarse and glassy. The HP-cassava and potato starches significantly increased in solubility by 79.4 and 14.7%, respectively. The HP-starches also exhibited a reduction in the volume of sedimentation, while only the HP-cassava starch showed a reduced water retention capacity of 1.7133 g/g. Percentage syneresis was lower in both HP-cassava and potato starches with 4.16 and 1.08%, respectively. The HP-cassava and potato starches showed excellent flowability with corresponding Carr’s indices of 5.96 and 5.23% and angles of repose of 19.98 and 20.50°, respectively. DSC and FTIR results confirmed starch modification while SEM showed smooth flat particles. Conclusion: Hydroxypropylation enhanced the solubility, reduced the volume of sedimentation and improved the freeze-thaw stability of the native starches. It also increased the water retention capacity and moisture sorption of potato starch.