Surface Chemical Compositions and Dispersity of Starch Nanocrystals Formed by Sulfuric and Hydrochloric Acid Hydrolysis

Benxi Wei,Zhengyu Jin,Yaoqi Tian,Xueming Xu,Vipul Bansal

doi:10.1371/journal.pone.0086024

Benxi Wei, Zhengyu Jin + Show 3 more

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https://doi.org/10.1371/journal.pone.0086024

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Abstract

Surface chemical compositions of starch nanocrystals (SNC) prepared using sulfuric acid (H2SO4) and hydrochloric acid (HCl) hydrolysis were analyzed by X-ray photoelectron spectroscopy (XPS) and FT-IR. The results showed that carboxyl groups and sulfate esters were presented in SNC after hydrolysis with H2SO4, while no sulfate esters were detected in SNC during HCl-hydrolysis. TEM results showed that, compared to H2SO4-hydrolyzed sample, a wider size distribution of SNC prepared by HCl-hydrolysis were observed. Zeta-potentials were −23.1 and −5.02 mV for H2SO4- and HCl-hydrolyzed SNC suspensions at pH 6.5, respectively. Nevertheless, the zeta-potential values decreased to −32.3 and −10.2 mV as the dispersion pH was adjusted to 10.6. After placed 48 h at pH 10.6, zeta-potential increased to −24.1 mV for H2SO4-hydrolyzed SNC, while no change was detected for HCl-hydrolyzed one. The higher zeta-potential and relative small particle distribution of SNC caused more stable suspensions compared to HCl-hydrolyzed sample.

Highlights

There has been growing interest in starch nanocrystals (SNC) for abundant availability of starch, comparatively easy processability, biocompatibility, biodegradability, and non-toxicity, comparing with inorganic nanoparticles [1]
It was reported that SNC derived from H2SO4 hydrolysis resulted in more stable suspensions than hydrochloric acid (HCl) hydrolyzed samples [11]
Small amounts of nitrogen atoms were detected in the Waxy maize starch (WMS) due to the protein presented on the surface, which was in agreement with the report of Rindlav-Westling & Gatenholm [22]

Summary

Introduction

There has been growing interest in starch nanocrystals (SNC) for abundant availability of starch, comparatively easy processability, biocompatibility, biodegradability, and non-toxicity, comparing with inorganic nanoparticles [1]. It was reported that SNC derived from H2SO4 hydrolysis resulted in more stable suspensions than HCl hydrolyzed samples [11].

Results

Conclusion