Evaluating Dough Density Changes During Fermentation by Different Techniques

Abstract

Producing an aerated bread dough starts at the mixing stage where air bubble nuclei are incorporated into the dough. During fermentation, the production of CO2, due to yeast’s metabolic activities, causes the bubbles to increase in size thereby increasing the volume and reducing the density. Therefore, the way in which the density of the dough is reduced and the dough’s ability to retain gas plays an important part in the production of good loaf volume. A number of studies have used different approaches to examine the effects of fermentation conditions on the rheology of dough. The internal pressure of fermenting dough has been measured by placing the dough in a glass cylinder (Matsumoto et al 1971). The expansion of the dough resulting from fermentation was studied by Miller at al (1954), who measured the expansion by displacement of a weak salt solution. In another study (Marek and Bushuk 1966), the buoyancy of fermenting dough was measured by placing it on a balance in a constant temperature bath of mineral oil. However, despite the importance of dough density changes as an indicator of gas holding capacity of the dough, a direct comparison of how the density changes as the dough ferments using a variety of measurement techniques has not been reported. The objective of this note was to investigate the effect of measurement techniques on evaluation of dough density by measuring the decrease in density of fermenting dough under different geometrical constraints and comparing the results. To achieve this, the volume of the expanding dough was measured over time using three methods: 1) dough height increase within a graduated cylinder, 2) water displacement following free expansion of subsamples of the dough, and 3) radial expansion of dough constrained between two thick acrylic plates (measured using digital imaging).