Thesis (M.Sc.) - Cairo University - Faculty of Agriculture - Department of Food Science and Technology

The present study was performed to investigate physicochemical characteristics of sourdough of pan and balady bread that made by mixed culture from yeast and probiotic bacteria (Lactobacillus plantarum, Lactobacillus heleveticus, Leuconostuc mesenteroides and Bifidobacterium bifidum), as a form of free or encapsulated cells. Percentage of yeast in pan and balady bread was (1.5%), while probiotic bacteria were added as a percentage of 5% either pan or balady bread. Results revealed that sourdough samples mixed by Leu. mesenteroides during incubation time (120 min) had the highest amount of gas production in dough of wheat flour 72% while, in dough of wheat flour 82% was sample prepared by B. bifidum compared with two control samples Production of organic acids (lactic and citric acids), CO₂, extend shelf-life and organoleptic quality of the sourdough bread were evaluated. Sourdough sample of pan bread containing L. plantarum had the highest titratable acidity (6.48), the lactic acid concentration was the highest with the sample fermented by encapsulated Leu. mesenteroides (11.75g/kg). Sample prepared by B. bifidum showed high resistance of mold and yeast after 7 days of storage at room temperature (6.07 Log CFU/g). Likewise, sample prepared by encapsulated L. heleveticus was the highest specific volume (3.54) and improved texture profile of pan bread

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