Shear degradation of corn starches with different amylose contents

Liu, Xingxun, Xiao, Xiaoming, Liu, Peng, Yu, Long, Li, Ming, Zhou, Sumei and Xie, Fengwei (2017) Shear degradation of corn starches with different amylose contents. Food Hydrocolloids, 66 199-205. doi:10.1016/j.foodhyd.2016.11.023

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Author Liu, Xingxun
Xiao, Xiaoming
Liu, Peng
Yu, Long
Li, Ming
Zhou, Sumei
Xie, Fengwei
Title Shear degradation of corn starches with different amylose contents
Journal name Food Hydrocolloids   Check publisher's open access policy
ISSN 0268-005X
Publication date 2017-05-01
Year available 2016
Sub-type Article (original research)
DOI 10.1016/j.foodhyd.2016.11.023
Open Access Status File (Author Post-print)
Volume 66
Start page 199
End page 205
Total pages 7
Place of publication Amsterdam, Netherlands
Publisher Elsevier BV
Collection year 2018
Language eng
Formatted abstract
This work investigated the effect of shear on the starch degradation, with a particular focus on the changes in molecular and lamellar structures. Corn starches with different amylose/amylopectin ratios (waxy corn starch, or WCS: 1:99; normal corn starch, or NCS: 25:75; and Gelose 80 starch, or G80: 80:20) were used as model materials to be processed using a Haake twin-rotor mixer for different times. Molecular and lamellar structural analysis was performed using size-exclusion chromatography (SEC) and small-angle X-ray scattering (SAXS). The degree of damage of starch at the granule level was evaluated by an assay kit. The results showed that amylose molecules in starch granules did not change significantly, while amylopectin molecules degraded to a stable size caused by the shear treatment. The average thickness of semi-crystalline lamellae disappeared rapidly during processing. A typical positive deviation from Porod's law at a high q region was observed, attributed to the presence of thermal density fluctuations or mixing within phases. Nonetheless, the degree of mixing within phases for the processed samples was lower than the native starch. The study of the mass fractal structure indicated that the scattering objects of the processed starches were more compact than those of the native counterparts. Furthermore, waxy corn starch (containing mostly amylopectin) experienced the greatest granule damage than the other starches. All the results showed that the rigid crystal structure in amylopectin is more sensitive to the shear treatment than the flexible amorphous structure in amylose. This mechanistic understanding at the microstructure level is helpful in designing the processing of starch-based foods or plastics with desired functional properties.
Keyword Amylose
Lamellar structure
Shear strength
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemical Engineering Publications
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