Thesis (Ph.D.) - Cairo University - Faculty of Agriculture - Department of Food Science and Technology

The present study was aimed to improve the quality characteristics and shelf-life of balady bread and pan bread by using sour dough starter that fermented with 2% saccharomyces cerevisiae+1, 2 or 3% Lactobacillus plantarum. Microbial counts (i.e. lactic acid bacteria, total bacterial count and yeasts), pH, phytic acid content, organic acids and antimicrobial activity were evaluated during sour dough incubation. Results showed a significant increase in LAB and yeast count accompanied with a significant reduction in total bacterial count during incubation period. A significant increase in organic acids and antimicrobial activity accompanied by a reduction in pH, and degradation of phytic acid content, during the incubation of different sour dough starters were recorded. These metabolites increased by increasing lactic acid bacteria ratio in sour dough (3%>2%>1% L. plantarum). Antimicrobial activity of wheat flour dough and balady bread containing 20% different sour dough starters were evaluated and the results showed that dough and bread fermented with 3% L. plantarum exhibited the highest antimicrobial activity against the pathogenic microorganisms. Bread characteristics showed an increase of shelf-life for 6 days in samples containing sour dough (3% L. plantarum) comparing to 2 days for control one. Fermentation of pan bread dough with 20% sour dough containing 2 or 3% L. plantarum retarded the staling rate of bread loaves by 13.40% and 12.90% after 3 days comparing to control sample (23.03%), respectively. Improvements in sensory characteristics and acceptability of balady and pan bread were also recorded by using sour dough starter. Flavor of pan bread was also improved by fermentation with sour dough. Accordingly, this could increase the bread acceptability, reduce the overall bread losses and consequently reduce the total amount of wheat flour used

Issued also as CD