Microbial populations associated with commercial bread production

The microbial ecology of a commercial bread production line was assessed by plate counts and characterization of microbial populations of raw materials, dough, equipment surfaces, air inside the bakery and baked bread. Aerobic plate counts for raw materials were higher than mould counts. Dough samples had high aerobic plate counts, but low mould counts. Mould counts on pre-baking equipment surfaces were lower than those on post-baking equipment surfaces, while aerobic plate counts on equipment surfaces varied. Counts of bacteria and moulds on bread increased during storage at 30 degrees C and moulds predominated over bacteria on air settle plates. Of the 316 bacterial isolates, 50% were Bacillus and 31.6% Micrococcus. Of the 97 mould isolates, 37.1% were Penicillium, 18.6% Aspergillus and 13.4% Cladosporium. Bacillus, Aspergillus and Penicillium were isolated predominantly from baked bread.