Starch structure – Property relations for digestion of cooked rice

Zainul Abidin, S., Hasjim, J. and Gilbert, R. G. (2010). Starch structure – Property relations for digestion of cooked rice. In: Abstracts: 2010 AACC International Annual Meeting. AACC International Annual Meeting 2010, Savannah, GA, USA, (A77-A77). 24-27 October 2010.

Author Zainul Abidin, S.
Hasjim, J.
Gilbert, R. G.
Title of paper Starch structure – Property relations for digestion of cooked rice
Conference name AACC International Annual Meeting 2010
Conference location Savannah, GA, USA
Conference dates 24-27 October 2010
Proceedings title Abstracts: 2010 AACC International Annual Meeting   Check publisher's open access policy
Journal name Cereal Foods World   Check publisher's open access policy
Place of Publication St. Paul, MN, United States
Publisher American Association of Cereal Chemists
Publication Year 2010
Sub-type Published abstract
ISSN 0146-6283
Volume 55
Start page A77
End page A77
Total pages 1
Language eng
Formatted Abstract/Summary
Seven Malaysian rice varieties (amylose content ranging from 0.2 to 27%)
were subjected to in-vitro digestion with a multi-step process that mimics
digestion in humans. The rice was cooked, ground and digested and digestate
collected at various times. The kinetics of starch hydrolysis during the
digestion fitted the Michaelis-Menten mechanism. As expected, higher Vmax
values were obtained for two waxy samples compared with the rice samples
with higher amylose contents; however, the Km values did not show any
correlation to amylose content. These results are consistent with the
assumption that amylose chains tending to leach from the granules during
cooking, forming a viscous network that encapsulates the starch granules,
making them less accessible to pancreatic alpha-amylase and slowing the
enzymic process, resulting in the lower Vmax values. The time evolutions of
the size distributions of the whole and debranched starch in the undigested
fractions were obtained using multiple detection size-exclusion chromatography
(SEC). The starch was extracted using an improved extraction/dissolution
technique for complete starch extraction and dissolution without degradation.
This gave the size dependences of the weight distribution, number distribution,
weight average molecular weight and radius of gyration. Trimodal
chromatograms were observed for all digested samples, which consisted of
amylose, amylopectin and intermediate materials (size range 10–20 nm). The
three peaks persisted until the end of digestion analysis (6 h), only with
decreased amounts over time. This showed that the starch molecules in the
cooked rice grains were hydrolyzed in a controlled fashion without much
molecular size selection. This may be caused by the large size of entities in the
sample, which limited the action of digestion enzymes to the sample surfaces.
Subjects 090801 Food Chemistry and Molecular Gastronomy (excl. Wine)
030403 Characterisation of Biological Macromolecules
Q-Index Code CX
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Conference Paper
Collection: Centre for Nutrition and Food Sciences Publications
 
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Created: Wed, 09 Mar 2011, 23:29:21 EST by Mr Jovin Hasjim on behalf of Centre for Nutrition and Food Sciences