How the structure and physical chemistry of dietary fibre can help make healthier foods

Haider, Kathrin (2022) How the structure and physical chemistry of dietary fibre can help make healthier foods. Doctoral thesis, University of East Anglia.

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There is substantial evidence supporting the beneficial health effects of dietary fibres. Due to the huge diversity of dietary fibres, it is highly challenging to classify them in a manner to predict health outcomes in humans. The overall aim of this thesis was to link the physico-chemical properties of a range of dietary fibres to their functionality in physiological mechanisms in duodenal digestion.

Cereal brans as well as isolated fibres like β-glucan, inulin and cellulose were characterised in terms of rheological, colligative or binding properties. This information is used to understand the impact of dietary fibre on lipid digestion, dietary fibre interaction with bile acids as well as dietary fibre’s effect on starch gelatinisation and digestion in in vitro digestion models.

Barley fibres appeared more potent in delaying lipolysis than oat fibres. The presence of insoluble dietary fibre was found to enhance the effects of oat β-glucan. Lipase activity was reduced substantially by both barley and oat brans but not to the same extent by its β-glucan extracts. Barley and oat bran retained bile acids but purified β-glucan did not. Cereal dietary fibre has the potential to slow down lipid digestion via increased viscosity, bile acid and/or lipase interaction. The physico-chemical properties of the isolated fibres β-glucan, inulin and cellulose determined their impact on starch gelatinization via acting as a plasticizer or water competitor. This was tested in a realistic food matrix by incorporating dietary fibre into biscuits, which led to reduced starch digestibility with one of the tested inulins.

This research in combination with the current literature helps to classify the different forms of fibre, their behaviour during digestion, and the resulting physiological benefits. Important properties of dietary fibres for health benefits are physiological solubility, viscosity, interaction with water and physico-chemical binding.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 24 Apr 2023 10:01
Last Modified: 24 Apr 2023 10:01

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