Freeze-drying changes the structure and digestibility of B-polymorphic starches

Zhang, Bin, Wang, Kai, Hasjim, Jovin, Li, Enpeng, Flanagan, Bernadine M., Gidley, Michael J. and Dhital, Sushil (2014) Freeze-drying changes the structure and digestibility of B-polymorphic starches. Journal of Agricultural and Food Chemistry, 62 7: 1482-1491. doi:10.1021/jf405196m

Author Zhang, Bin
Wang, Kai
Hasjim, Jovin
Li, Enpeng
Flanagan, Bernadine M.
Gidley, Michael J.
Dhital, Sushil
Title Freeze-drying changes the structure and digestibility of B-polymorphic starches
Journal name Journal of Agricultural and Food Chemistry   Check publisher's open access policy
ISSN 0021-8561
Publication date 2014-02-19
Year available 2014
Sub-type Article (original research)
DOI 10.1021/jf405196m
Open Access Status Not yet assessed
Volume 62
Issue 7
Start page 1482
End page 1491
Total pages 10
Place of publication Washington, DC, United States
Publisher American Chemical Society
Language eng
Subject 1600 Chemistry
1100 Agricultural and Biological Sciences
Abstract Starch granules both isolated from plants and used in foods or other products have typically been dried. Common food laboratory and industry practices include oven (heat), freeze, and ethanol (solvent-exchange) drying. Starch granules isolated from maize (A-type polymorph) and potato (B-type polymorph) were used to understand the effects of different dehydration methods on starch structure and in vitro digestion kinetics. Oven and ethanol drying do not significantly affect the digestion properties of starches compared with their counterparts that have never been dried. However, freeze-drying results in a significant increase in the digestion rate of potato starch but not maize starch. The structural and conformational changes of starch granules after drying were investigated at various length scales using scanning electron microscopy, confocal laser scanning microscopy, X-ray diffraction, FTIR spectroscopy, and NMR spectroscopy. Freeze-drying not only disrupts the surface morphology of potato starch granules (B-type polymorph), but also degrades both short- and long-range molecular order of the amylopectin, each of which can cause an increase in the digestion rate. In contrast to A-polymorphic starches, B-polymorphic starches are more disrupted by freeze-drying, with reductions of both short- and long-range molecular order. We propose that the low temperatures involved in freeze-drying compared with oven drying result in greater chain rigidity and lead to structural disorganization during water removal at both nanometer and micrometer length scales in B-type polymorphic starch granules, because of the different distribution of water within crystallites and the lack of pores and channels compared with A-type polymorphic starch granules.
Keyword Crystalline structure
Granule morphology
In vitro digestion
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Queensland Alliance for Agriculture and Food Innovation
Official 2015 Collection
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Citation counts: TR Web of Science Citation Count  Cited 22 times in Thomson Reuters Web of Science Article | Citations
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