Effect of Formulation and Processing Treatments on Viscosity and Solubility of Extractable Barley β-Glucan in Bread Dough Evaluated Under In Vitro Conditions

beta-Glucan shows great potential for incorporation into bread due to its cholesterol lowering and blood glucose regulating effects, which are related to its viscosity, The effects of beta-glucan concentration, gluten addition, premixing, yeast addition, fermentation time, and inactivation of the flour enzymes on the viscosity of extractable beta-glucan following incorporation into a white bread dough were studied under physiological conditions, as well as, beta-glucan solubility in fermented and unfermented dough. beta-Glucan was extracted using an in vitro protocol designed to approximate human digestion and hot water extraction. The viscosity of extractable beta-glucan was not affected by gluten addition, the presence of yeast, or premixing. Fermentation produced lower (P <= 0.05) extract viscosity for the doughs with added beta-glucan, while inactivating the flour enzymes and increasing beta-glucan concentration in the absence of fermentation increased (P <= 0.05) viscosity. The physiological solubility of the beta-glucan concentrate (18. 1 %) and the beta-glucan in the unfermented dough (20.5%) were similar (P > 0.05), while fermentation substantially decreased (P : 0.05) solubility to 8.7%, indicating that the reduction in viscosity due to fermentation may be highly dependent oil solubility in addition to beta-glucan degradation. The results emphasize the importance of analyzing beta-glucan fortified foods under physiological conditions to identify the conditions in the dough system that decrease beta-glucan viscosity so that products with maximum functionality can be developed.