Barley beta-glucan in bread: the journey from production to consumption

  • Author / Creator
    Moriartey, Stephanie
  • β-Glucan is a soluble fibre shown to help regulate blood sugar and lower cholesterol. Incorporation into food, particularly bread, may affect β-glucan’s physicochemical properties and health benefits. The journey of β-glucan through the mixing, fermenting, baking, and storage of bread was evaluated, in terms of its solubility and viscosity under in vitro physiological conditions, at levels most likely to be presented to consumers (0.75, 1.0, 1.5 g β-glucan/serving). Satiety and glycemic response measures, in addition to the quality and consumer acceptability of the bread, were also investigated. In dough, viscosity of the physiological extract was impacted by β-glucan level, fermentation time, and endogenous flour enzymes. Fermentation decreased β-glucan solubility indicating that the reduction in viscosity depends on both molecular degradation and solubility reduction. Dough rheological properties and microstructure, characterized using an oscillatory rheometer and fluorescence microscopy, respectively, showed that β-glucan may interfere with the gluten network, though gluten addition may help improve this. The bread’s physical properties supported these observations, as β-glucan decreased loaf volume and height, while gluten addition corrected this. Baking increased β-glucan solubilization to 58-60%, compared to 9% in dough. Gluten addition increased solubility further (67-68%). Similar trends were seen for extract viscosity and were supported by fluorescence microscopy images. Storage at ambient, refrigeration and frozen conditions showed that bread with β-glucan should be consumed fresh to maintain highest bread quality and β-glucan solubility and viscosity. Bread with β-glucan kept panelists full, longer. Reducing sugar release values implied that satiety may depend on digesta viscosity and/or rate of sugar release from the bread. Bread with β-glucan produced the most leveled glucose curve; though areas under the 2 hr plasma glucose curves were similar. Consumers liked the 0.75 g β-glucan/serving bread and the control more than the 1.5 g β-glucan/serving bread, though provision of health information improved bread liking to similar values. The findings demonstrate that low solubility β-glucan concentrate that gets solubilized upon baking is well suited for bakery applications and that a successful β-glucan-fortified bread product is possible. Commercialization of bread fortified with β-glucan would provide consumers an additional source of dietary fibre to assist them in coming closer to recommended daily intakes.

  • Subjects / Keywords
  • Graduation date
    Fall 2009
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.