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.

Method: 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 HPstarches were off-white, coarse and glassy. The HPcassava and potato starches  significantly increased in solubility by 79.4 and 14.7%, respectively. The HPstarches 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 HPcassava 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.