Associated mycoflora of rye bread

Penicillium roqueforti (27%), P. corylophilum (20%) and Eurotium species (15%) made up the important mycoflora associated with rye bread on 3425 identified fungi isolates. These fungi were dominant as spoilers of packaged rye bread in almost every month of a 4 year investigation. Penicillium decumbens (3%), Paecilomyces variotii (8%) and Aspergillus flavus (5%) were found more rarely, but were the major species found over periods of a few months. Penicillium commune (5%), P. solitum (4%), A. niger (4%) and Mucor species (2%) were a constant, but small, part of the total mycoflora of rye bread. Identification of the fungi in the production environment in a rye bread factory showed the locality of potential contamination sources. Elimination of the contamination sources by improved cleaning and disinfection procedures quickly resulted in a significant reduction in the frequency of mould growth in the packaged rye bread.