Supramolecular structure and thermal behavior of cassava starch treated by oxygen and helium glow-plasmas

Abstract

The thermal property of cassava starch was regulated by the oxygen or helium glow-plasma treatment to change its supramolecular hierarchical structure. By investigating the microstructural and mesoscopic scale structural alterations and the thermal transition without and with the glow-plasma treatment, the underlying mechanism was explored through establishing a structure–thermal property relationship. Particularly, while there were negligible changes to the granule morphology, the glow-plasma predominantly disorganized the crystallites with low perfection and thermal stability, resulting in decreased alignment of double-helices within the crystalline lamellae, reduced relative crystallinity and thermal transition enthalpy, and increased transition temperatures accompanied by a narrowed gelatinization temperature range. The thermal transition parameters could be further modulated by simply changing the atmosphere type and treatment time. This is much different from our previous study which showed if glow-plasma disrupted the supramolecular structure of starch, the thermal transition temperatures would be reduced. These findings from present study indicate that the glow-plasma treatment can serve as a highly-safe physical method to rationally regulate the hierarchical structure of cassava starch and thus to realize the development of starch-based products with desired thermal behavior.