Cryo-milling of starch granules leads to differential effects on molecular size and conformation

Dhital, Sushil, Shrestha, Ashok K., Flanagan, Bernadine M., Hasjim, Jovin and Gidley Michael J. (2011) Cryo-milling of starch granules leads to differential effects on molecular size and conformation. Carbohydrate Polymers, 84 3: 1133-1140. doi:10.1016/j.carbpol.2011.01.002

Author Dhital, Sushil
Shrestha, Ashok K.
Flanagan, Bernadine M.
Hasjim, Jovin
Gidley Michael J.
Title Cryo-milling of starch granules leads to differential effects on molecular size and conformation
Journal name Carbohydrate Polymers   Check publisher's open access policy
ISSN 0144-8617
Publication date 2011-03-17
Sub-type Article (original research)
DOI 10.1016/j.carbpol.2011.01.002
Volume 84
Issue 3
Start page 1133
End page 1140
Total pages 8
Place of publication Kidlington, England, U.K.
Publisher Pergamon
Collection year 2012
Language eng
Abstract Milling of starch granules is important for many food applications and involves a combination of mechanical and thermal energy. In order to understand the effects of mechanical force alone, four commercial starches including maize starch (MS), potato starch (PS), and two high amylose maize starches (HAMS) (Gelose 50 and Gelose 80) were cryo-milled for 20 min under the same conditions. The structural and conformational changes of the starches after cryo-milling were evaluated using X-ray diffraction, NMR spectroscopy, IR and Raman spectroscopy, and size exclusion chromatography (SEC). The cryo-milled starches had less crystallinity (15-35%) and 35-50% less ordered structure (double and single helices) than the native starch counterparts. The gelatinisation temperatures of the starches were not significantly altered by cryo-milling, but the gelatinisation enthalpies were significantly reduced in line with the reductions in the amount of double helices. Although, all four starches showed similar extent of degradation of crystalline/ordered structure, SEC results showed a greater degradation of amylopectin molecule in MS and PS than in HAMS. Increased amylose content in starch seemed to reduce the molecular degradation during milling, which is consistent with a role for amylose as a mechanical plasticiser in starch granules. It is concluded that (i) cryo-milling has differential effects on molecular size and conformation depending on starch granule type, and (ii) deterioration of starch crystalline and molecular order by mechanical treatment is not necessarily linked with the reduction in molecular size. The implication from the results is that the mechanical forces acting during cryo-milling are capable of disrupting helical and crystalline structures without breaking covalent bonds of starch molecules. © 2011 Elsevier Ltd. All rights reserved.
Keyword Amylopectin
Molecular size
Starch granules
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Available online 12 January, 2011.

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2012 Collection
Centre for Nutrition and Food Sciences Publications
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Created: Mon, 14 Feb 2011, 17:23:41 EST by Mr Sushil Dhital on behalf of Centre for Nutrition and Food Sciences