118 Factors influencing yeast fermentation in wheat flour dough and the effect of yeast fermentation on bread quality.

S. Sahlstrom (1), W. J. Park (2), and D. R. Shelton (2). (1) MATFORSK, Norwegian Food Research Institute, Osloveien 1, N-1430 Ås, Norway; (2) Dept. of Agronomy, Inst. of Agriculture and Natural Resources, Univ. of Nebraska, Lincoln, NE 68583-0915.

The ability of bakers yeast to ferment wheat flour dough is related to the amount of fermentable sugars in the flour, including maltose produced from starch hydrolysis. Yeast, in the presence of fermentable sugars, produces carbon dioxide gas. Yeast fermentation in bread dough expands cells, creating the open crumb structure of baked products. The rate of yeast fermentation is, therefore, important to measure. The purpose of this study was to investigate how the dough components (flour, water and yeast) and mixing time affect yeast fermentation. To test this, 36 different flours were produced from 2 different mills, using 6 different wheat varieties grown at 3 locations. The content of damage starch and mono and disaccharides in each flour were monitored. Fermentation rate and maximum gas pressure in dough samples were determined using a modified pressuremeter and GasSmart software (National Mfg. Co., Lincoln, Nebraska). Bread was baked using flour from one of the mills. Yeast fermentation varied among the flour tested and was affected by growth location and type of mill. The pore structure of the bread crumb (crumb score) was affected by yeast fermentation.