Microfluidization has been applied to modify starch granules. The study was conducted to investigate the effect of microfluidization on the structure and thermal properties of cassava starch–water suspension (20% w/w). The means of optical microscopy, SEM, FTIR spectroscopy, XRD, and DSC were applied to analyze the changes in microstructure, crystallinity, and thermal property. Microscopy observations revealed that native starch granules were oval, round, and truncated in shape. After the microfluidization treatment, a bigger starch granule was partially gelatinized, and a gel‐like structure was formed on a granular surface. No significant difference in XRD patterns of the samples were observed and all samples exhibited A‐type allomorph. Crystallinity decreased with the pressure. Sample treated at 150 MPa contains 17.1% crystalline glucan polymer, lower than that of native granules which have crystallinity of about 25.8%. A lower crystallinity means poor order of crystalline glucan polymer structure in starch granules. The disruption of crystalline order within the granule was also observed by FTIR measurement. Thermal analysis using DSC indicated that the microfluidization treatment brought about a significant decrease of melting enthalpy. The gelatinization enthalpy was 12.0 and 3.0 J/g for the native sample and samples treated under the 150 MPa, respectively. The results indicate that high‐pressure microfluidization process induced the gelatinization of cassava starch, which is evaluated by a percentage of the degree of gelatinization, due to a pronounced decrease with increasing microfluidizing pressure.

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Granule Sizes of Canna (Canna edulis) Starches and their Reactivity Toward Hydration, Enzyme Hydrolysis and Chemical SubstitutionSmall and large granule fractions were isolated from canna starch (Canna edulis, green leaf cultivar), and their morphology, physicochemical properties, susceptibility towards granular starch hydrolyzing enzymes and chemical reaction with propylene oxide were investigated. Canna starch consisted of a mixed population of large, medium and small granules; the mean of granule diameter was 47.4 mm. The small granules presented round and polygonal shapes, whereas the large granules had oval and elliptical shapes. Significant variations in digestibility of the various granules size by granular starch hydrolyzing enzymes were observed. During the first 24 h, the hydrolysis rate of small granules was higher than that of native and large granule starches. After 72 h, however, the degree of hydrolysis of small granule, large granule and native starches had reached the extent of 19.6%, 32.0% and 27.2%, respectively. The larger the granule size, the higher the MS obtained when modified with propylene oxide, which was due to the higher swelling power of the large granules. The results obtained from this study suggest that small granules had lower water and chemical affinity when compared with the bigger ones. The difference in the reactivity of small and large granules could be presumably attributed to the starch components (amylose and amylopectin) and their organization of glucan chains in ordered and/or less ordered structure of these two fractions.