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Spherulitic crystallization in starch as a model for starch granule initiation
Gregory R Ziegler1, John A Creek, James Runt
1The Pennsylvania State University, 116 Borland Lab, University Park, Pennsylvania 16801, USA. grz1@psu.edu
Biomacromolecules
|May 10, 2005
Summary
Mung bean starch forms spherulites when heated to 180°C and cooled below 65°C, with formation influenced by cooling rates. This study models in vivo starch granule initiation via spherulitic crystallization.
Area of Science:
- Food science and technology
- Biopolymer crystallization
- Materials science
Background:
- Starch morphology influences its functional properties.
- Understanding starch crystallization is key to controlling food texture and processing.
- Mung bean starch is a common food ingredient with unique properties.
Purpose of the Study:
- To investigate the effect of cooling rate and quench temperature on mung bean starch spherulite formation.
- To characterize the morphology and thermal properties of the resulting crystalline structures.
- To propose a model for starch granule initiation based on observed crystallization.
Main Methods:
- Heating mung bean starch to 180°C.
- Controlled cooling at rates from 2.5 to 250°C/min.
- Differential Scanning Calorimetry (DSC) for thermal analysis.
- X-ray diffraction (XRD) for structural analysis.
Main Results:
- Spherulites formed when cooled below 65°C, across a broad range of cooling rates.
- Branched crystalline and gel-like morphologies were also observed.
- Spherulitic material dissolved between 100-130°C; gel-like material showed a second endotherm at 130-150°C.
- X-ray diffraction revealed B-type patterns for spherulites.
Conclusions:
- Cooling rate and quench temperature significantly impact mung bean starch morphology.
- Spherulitic crystallization following phase separation is a plausible mechanism for in vivo starch granule initiation.
- The findings contribute to understanding starch structure-property relationships.