Understanding the intrinsic and extrinsic properties of a starch branching enzyme II wheat mutant and their impact on glucose response

Oct 3, 2026

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Wheat is a major dietary carbohydrate source, yet many wheat products are rapidly digested, producing elevated post-meal blood glucose. This PhD examined a wheat mutant carrying mutations in starch branching enzyme II (sbeII) genes, focusing on starch properties, susceptibility to amylolysis, processing effects, and glycaemic potential. In vitro work showed starch retrogradation limits sbeII starch amylolysis. Two in vivo double-blind crossover studies assessed glycaemic impact using sbeII semolina pudding and bread, suggesting reduced response, with further confirmation needed.

LanguageEnglish

CategoryResearch & Report

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Pages317

Reading Time13 h 19 min

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Understanding the intrinsic and extrinsic properties of a starch branching enzyme II wheat mutant and their impact on glucose response Marina Corrado Quadram Institute Bioscience A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy University of East Anglia School of Biological Science November 2020 © This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with the author and that use of any information derived there from must be in accordance with current UK Copyright Law. In addition, any quotation or extract must include full attribution. Abstract Wheat is a major source of dietary carbohydrate but the starch in many wheat-based products is rapidly digested, causing a rapid increase in blood glucose levels after consumption. Previous research has developed a novel type of wheat carrying mutations in starch branching enzyme II a and b (sbeII) genes, characterised by altered starch structure, thought to be less susceptible to amylolysis. The sbeII wheat is known to have a higher amylose content than conventional wheat, but its processing performance, starch digestibility and glycaemic power have not yet been studied in detail. The aims of this PhD project were to examine the intrinsic and extrinsic properties of starch from a sbeII wheat, to investigate its susceptibility to starch amylolysis in vitro, and explore its potential use to lower glycaemic response to wheat-based foods in vivo. A series of in vitro studies were undertaken to characterise the starch and non-starch polysaccharide components of sbeII wheat and to determine the effects of hydrothermal processing on sbeII starch susceptibility to hydrolysis. These studies demonstrated that starch retrogradation is a key mechanism limiting starch amylolysis in foods made with sbeII wheat. Based on this knowledge, two test foods (semolina pudding and bread) were then developed using sbeII wheat to measure the glycaemic impact of sbeII foods in vivo. Their effect on postprandial glycaemic response was determined in two double-blind cross-over intervention studies. Evidence from these in vivo studies suggested that sbeII bread canelicit a lower glycaemic response compared to the control bread, however, due to the relatively small size of the study cohort, the extent of the decrease in glycaemic response may need to be further investigated. Overall, these studies have advanced current understanding of sbeII wheat starch and its potential to improve glycaemic properties of wheat-based foods. Access Condition and Agreement Each deposit in UEA Digital Repository is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the Data Collections is not permitted, except that material may be duplicated by you for your research use or for educational purposes in electronic or print form. You must obtain permission from the copyright holder, usually the author, for any other use. Exceptions only apply where a deposit may be explicitly provided under a stated licence, such as a Creative Commons licence or Open Government licence. Electronic or print copies may not be offered, whether for sale or otherwise to anyone, unless explicitly stated under a Creative Commons or Open Government license. Unauthorised reproduction, editing or reformatting for resale purposes is explicitly prohibited (except where approved by the copyright holder themselves) and UEA reserves the right to take immediate ‘take down’ action on behalf of the copyright and/or rights holder if this Access condition of the UEA Digital Repository is breached. Any material in this database has been supplied on the understanding that it is copyright material and that no quotation from the material may be published without proper acknowledgement. Acknowledgements Firstly, I would like to thank my supervisors Dr Brittany H

FAQs

What is the main goal of this PhD project?

To characterize intrinsic and extrinsic properties of starch from the sbeII wheat mutant, assess susceptibility to amylolysis in vitro, and evaluate whether it can lower glycaemic response to wheat-based foods in vivo.

What did the in vitro studies show about why sbeII starch resists amylolysis?

Starch retrogradation was identified as a key mechanism limiting starch amylolysis in foods made with sbeII wheat.

How were the glycaemic effects tested in living subjects?

Two double-blind cross-over intervention studies measured postprandial glycaemic response using two test foods made with sbeII wheat: semolina pudding and bread.

Oct 3, 2026

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