Adsorption of Oxygen Gas by Hydrated Wheat Flour

Abstract

The concentration of free O2in a slurry made from flour and water was measured by a Clark O2electrode. As the flour/water (weight/weight) ratio increased from 0 to 0.5, the detected O2decreased from 100 to ~0% relative to the normal O2dissolved in water (0.28 mM). Similar O2depletion was also observed in aqueous suspensions of isolated wheat starch and wheat starch-gluten mixture (but not gluten). When samples of unbaked and baked 'Basic White Bread' dough were suspended in anaerobic water, free O2was slowly released into water. Based on the O2electrode measurement, the amount of released O2from fresh, half, and fully baked dough was assayed as ~500, 66, and 33% of that calculated from the aerated water used to make the dough. These results indicated that there exists an O2adsorption-desorption process by hydrated flour (dough), and that the well known 'anaerobicity' in dough only refers to this physical depletion (adsorption) of free O2rather than chemical/biological consumption of total O2inside dough. The potential effect of this O2adsorption-desorption process on dough/bread properties is discussed. © 2001 Academic Press.