Influence of the soluble fibres inulin and oat β-glucan on quality of dough and bread
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Bread represents a suitable food product for the addition of functional ingredients, such as the cholesterol-lowering dietary fibre oat β-glucan and the prebiotic inulin. Therefore, these soluble fibres were incorporated into wheat as well as gluten-free bread, and their effects on rheological properties of the dough, on bread quality and on crumb microstructure were compared. The level of remaining β-glucan as well as its molecular weight was determined using an enzyme kit and size-exclusion chromatography. The addition of oat β-glucan resulted in a higher water addition level, whereas incorporation of inulin had the opposite effect. Rheological testing showed that the incorporation of oat β-glucan results in a more elastic dough. The baking characteristics mainly affected by fibre addition were volume and crust colour, with inulin increasing and oat β-glucan decreasing loaf-specific volume in the gluten-free breads. Inulin led to a darkening of the crust of both bread types, whereas addition of oat β-glucan resulted in a lighter crust of gluten-free bread. Oat β-glucan softened the crumb of gluten-free bread, but had the opposite effect on wheat bread. Inulin resulted in an increased crumb hardness as well as the rate of staling. Beta-glucan breakdown was more pronounced in wheat bread than in gluten-free bread. The results show that the use of β-glucan to increase the nutritional value of wheat bread is limited due to negative influences on technological properties. However, this soluble fibre is highly suitable for incorporation into gluten-free bread.
KeywordsGluten-free Wheat Prebiotic Beta-glucan Rheology
Funding for Anna-Sophie Hager was received through an EMBARK scholarship granted by the Irish Research Council for Science, Engineering and Technology (IRCSET). IRCSET’s initiatives are funded by the National Development Plan of Ireland under the auspices of the Department of Education and Science. This study was financially supported by the Food Institutional Research Measure, administered by the Department of Agriculture, Fisheries and Food, Ireland.
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