Microbiological analysis of flour and whole-grain bread

and biochemical indentification of bacterial isolates

Satchanska G., Doycheva A. and S. Panayotova

New Bulgarian University

Flour and whole-grain bread were analyzed for total aerobic bacteria content using the most probable number method. Four samples – white bread, brown bread, wheat-groats bread and wheat-grain bread were quantitatively and qualitatively examined. While the white and brown breads which were produced from flourcontain no preservatives and GMO the wheat-groatsand wheat-grain breads, produced from whole grains, contain additives as antioxidants, emulgators and E 282- calcium propionate as mould inhibitor. Our results showed that 1 cm³of each examined bread sample contain the following total number of aerobic bacteria:  1.8 x10⁶ -inthe white bread, 9.0x10⁶ - inthe brown bread, 8.9x 10⁴ – in the wheat-groats bread and 7.6x10³– in the wheat-grain bread. The probable reason for the higher number of bacteria in the white and brown bread is the lack of preservatives. 20 bacterial isolates were cultured andtheir morphology was microscopically analyzed. Bacteria obtained are motile cocci as well as short and long sized rods. Additionally Gram staining and spore analysis was done and the biochemical indentification of the isolates was performed via Polimicrotest.