Fundamental research on gluten-free bread

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Horstmann, Stefan W.
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University College Cork
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The interest in gluten-free products has increased drastically over the past decades. This is the result of advanced detection methods for gluten-related disorders and the lifestyle choices of consumers. Gluten plays a key role in the production of bread, due to its viscoelastic properties. The replacement of gluten in bread creates a major challenge for producers and scientists to overcome. A literature review as part of this thesis discussed the current state of gluten-free bread and the efforts made to improve it. The quality of gluten-free bread has improved but is still considered to be of poor quality in regard to texture and nutritional value. Based on this review it was concluded that there is a need for a more fundamental understanding of ingredient interactions in a gluten-free bread system. The gained knowledge could help to improve the quality and nutritional value of gluten-free bread. This thesis addresses this issue by characterising commercially available raw materials and their influence on a model bread system (potato starch, HPMC, salt, sugar, yeast, water). Protein supplementation (pea, carob, lupin, potato, soy) in the model bread system affected bread quality parameters, such as specific volume and crumb hardness. Statistical analysis showed strong correlations between the functional properties (foaming, solubility) of the proteins and the bread quality parameters. In addition, the potential of functional ingredients such as hydrocolloids (HPMC, xanthan gum, guar gum, locust bean gum, sodium alginate, pectin) at different concentrations (0.25,0.5, 1.0,1.5,2.0%) to improve the quality of the model bread system was evaluated. It was observed that the addition of sodium alginate and pectin increased the specific volume of the breads in comparison to the HPMC and offered a more consumer-friendly substitute. Furthermore, beer yeast strains of the species Saccharomyces cervisiae were applied to a model bread system (potato starch, pea protein, pectin, salt, sugar, yeast, water). The results generated revealed the potential use of beer yeasts in the model bread system. The activity of yeast, which is affected by temperature and time strongly influenced the size of the baked loaves and correlated with crumb hardness. Lastly, the addition of milled sprouts (amaranth, brown millet, corn, lentil, lupin, pea, quinoa) to improve the nutritional value and its effect on the quality of model-bread system was evaluated. A comprehensive analysis of chemical composition, dough rheology and final bread properties revealed no significant correlations. However, the addition of amaranth caused an improvement of the specific volume and crumb hardness in comparison to a control. The application and combination of the different ingredient groups showed an improvement of the bread formulation in comparison to the starting formulation. The gained fundamental knowledge about the effect of raw material in a gluten-free model bread system opens new opportunities to improve gluten-free bread. The study further suggests raw materials for the use in gluten-free bread production. It also revealed ingredients which could be used to satisfy the demand by consumers for improved nutritional value.
Gluten-free , Starch , Protein , Yeast , Hydrocolloid , Sprouted flour
Horstmann, S. W. 2018. Fundamental research on gluten-free bread. PhD Thesis, University College Cork.