Effect of yeast-fermented and sour-dough making processes on physicochemical characteristics of β-glucan in whole wheat/oat bread

Consumption of breads containing whole grains or functional ingredients rich in dietary fiber and β-glucans has shown a dramatic increase because of their health benefits. Since bioactivity of β-glucan has been linked with its physicochemical properties, the current study was designed to investigate the effects of straight-, sponge- and sour-dough bread making processes on physicochemical characteristics of β-glucan in whole wheat/oat bread. The presence of β-glucan-degrading enzymes in the whole wheat flour used in this study were found to depolymerize β-glucan at a rate of 0.054 min−1, causing a significant reduction in β-glucan molecular weight (Mw) during dough process. Sour- and sponge-doughs had lower rates of β-glucan depolymerization, resulting in breads with medium to high β-glucan Mw range (600-1087 kg/mol) compared to straight-dough method. Dough pH, titratable acidity and fermentation plus proofing time showed significant impacts on β-glucan Mw and viscosity, but not on solubility. Acetic and propionic acids were present in all doughs, whereas lactic acid was only found in sour-dough. Generally, sour-dough bread showed better potential over yeast-fermented breads in terms of preserving β-glucan Mw and viscosity during baking process when a blend of whole wheat flour and oat bran was used.