Ecological and enzymatic studies on fungi associated with biscuits in Egypt

Some 43 species and four varieties belonging to nineteen genera were collected from 30 samples of six types of biscuit on 30% sucrose and 1% starch Czapek-Dox agars at 28°C. The most contaminated samples were chocolate wafers with 327 and 195 colonies g⁻¹, 12 and 8 genara and 18 and 13 species on the media, respectively. Samples of wafers without jam and jam wafers were less contaminated with fungi. The most frequently isolated fungi on the two media were Alternaria alternata, Aspergillus alutaceus, A. fumigatus, A. niger, A. sydowii, Cladosporium cladosporioides, C. herbarum, Penicillium chrysogenum, P. janczewskii and yeasts (Saccharomyces spp.). The osmophiles, Eurotium amstelodami and E. repens, were infrequently isolated from chocolates and jam-wafer biscuits.All 69 isolates tested produced invertase and could produce 90%, respectively, amylase, caseinase, and catalase.