Morphological, Structural, and Thermal Properties of Starch Nanocrystals Affected by Different Botanic Origins

Abstract

Cereal Chem. 91(4):383-388Six types of starch nanocrystals were prepared from corn, barley, potato, tapioca, chickpea, and mungbean starches with an acid hydrolysis method. The yields and morphological, structural, and thermal properties of starch nanocrystals were characterized. Starch nanocrystals had yields ranging from 8.8 to 35.7%, depending on botanical origin. During acid hydrolysis, amylose was effectively degraded, and no amylose was detected in any starch nanocrystal. Shape and size of native starch granules varied between starches, whereas there was no obvious difference in shape among different types of starch nanocrystals. The average particle size of starch nanocrystals was mainly related to crystalline type of native starches. Compared with their native starch counterparts, changes in crystalline diffraction patterns of starch nanocrystals depended on the original botanical source and crystalline structure. Degree of crystallinity, melting temperature, and enthalpy of starch nanocrystals increased, whereas their thermal decomposition temperature decreased. Of six produced starch nanocrystals, potato starch nanocrystal had the lowest yield, degree of crystallinity, and onset and melting temperatures, the largest particle size, and obvious changes in crystalline diffraction pattern.

The influence of bound water on the FTIR characteristics of starch and starch nanocrystals obtained from selected natural sources

“…In all the cases a weak broad feature is also observed. All those peaks and the pattern suggest that starch and starch nanocrystals obtained are having A‐type crystalline structure . This is in agreement with the reports that starch and starch nanocrystals from cereals are in general having A‐type crystalline structure .…”

“…Onset temperature (T o ), peak temperature (T p ), completion temperature (T c ), and enthalpy of melting process (ΔH) were measured from DSC curves and the results are given in Table . In the present study, the maximum of the endothermic peak ranged between 110 and 150 °C, which is consistent with a previous study by Xu et al The temperature range is less than the reported values for the theoretical melting point of dry crystallites which is estimated at 160–210 °C . This is due to the presence of residual moisture in the samples considered.…”

“…The largest difference was found for wheat starch (9.7 °C) and lowest for sorghum (3.3 °C). Earlier reports indicate that the presence of sulfate groups on the surface of starch nanocrystals is responsible for the decrease in T d of starch nanocrystals compared to native starch …”

“…It has been reported earlier that, in general, cereal grain starches have “A” type crystalline structure. Influence of botanical origin on the properties of starch nanocrystals from some natural sources such as wheat, potato, mungbean has been reported . However, similar information on local varieties of cereal grains such as ragi ( Eleusine coracana ), sorghum ( Sorghum bicolour ) has not been reported.…”

Enhancing properties of polyvinyl alcohol film using sorghum starch nanocrystals – A cost effective filler from natural source

“…3(a), SS shows the characteristic 'A' type crystalline pattern similar to that shown by other grains 22 . SS exhibited strong intensity peak at 17.8°, 23.1° and two weak intensity peaks at 15.1° and 19.8°.…”