Hydration and physicochemical properties of small‐particle cassava starch

Abstract

Acid hydrolysis followed by ball milling was applied to cassava starch in order to fracture the granules. Lintnerisation led to degradation first in the amorphous domains and increased the crystallinity. The resulting increase in internal defects and brittleness made the granules more susceptible to breakage upon milling. Ball milling, although leading to some degree of crystallinity loss, could effectively reduce the size of acid-hydrolysed starch while the total double helix remained relatively unchanged. The resulting small-particle starch was structurally more heterogeneous (wider T m range). Swelling of small-particle starch was accompanied by solubilisation of water-soluble fragments at a temperature greater than 60°C. The properties of individual granules are strongly influenced by the hydration and physicochemical properties of their amorphous and crystalline domains.

Effect of acid‐ethanol treatment followed by ball milling on structural and physicochemical characteristics of cassava starch

“…According to Sanguanpong et al . 21, local heat generated during ball milling can cause crystallinity loss and the development of highly viscous “melted liquid” that acted as “cement” gluing various starch granules.…”

“…Physical modification of starch in conjunction with chemical modification has been used for changing the granular structure and to convert native starch into soluble starch or into small crystallites of starch 19. The application of a physical force through ball milling on starch has shown to be effective for obtaining granules of very small size mainly after a pre‐treatment with enzyme or acid to weaken the granular structure 19–22. Cornstarch modified by acid in aqueous, alcoholic, or aqueous‐ alcoholic medium provided fragile granules that could be broken into small particles by friction in a pestle or by ball milling 19, 20.…”

“…Sanguanpong et al . 21 treated cassava starch with acid followed by ball milling and observed that the mechanical damage on the granules caused the change of the granule structure from ordered to disordered (amorphous) through the breaking of intermolecular linkages. Fractures observed in the broken part of the granules after milling were parallel to the growing axis of amylopectin chains, contrary to acid hydrolysis that preferentially breaks the glycosidic linkages in the growing ring.…”

Preparation and structural properties of small‐particle cassava starch

“…However, this does not imply that the starch residues still contain a similar double helical structure, as this can be affected by starch annealing. 28 When subjected to physical forces, a starch granule, still retains its overall shape, but its surface changes considerably. 29 Ball-milled granules lose their surface smoothness and become rough and disrupted.…”

“…Ball-milled starches are therefore expected to have altered hydration properties. 28 It is clear that, to effectively break down starch granules into small pieces, their amorphous regions should be removed exhaustively. The acid-hydrolysed starch with less amorphous structure can be disintegrated more readily than the enzyme-hydrolysed starch.…”