[Comparison of methods for the quantitative detection of moulds in foods. III. Comparison of different culture media for the mould plate count (author's transl)].

The mould plate count and taxonomical grouping of the mould flora of 9 moulded non-fluid foods were compared on totally 12 different media, which are commonly used for the detection of moulds.--In contrary to the bacteriological practice, moulds should only be counted on plates with 20-50 colonies, as on plates covered densely with a mixed mould flora, simple colonies are often no more detectable. Mould plate counts of all tested products were in the same range on all media with a sugar content of 1-2% (dextrose, maltose). With fruits and vegetables, less colonies were isolated on the Sugar Free Agar, Yeast Extract Agar and Aspergillus Differential Medium than on the other media. On those three media and on Plate Count Agar sporulation of many fungi was rather inhibited. On Aspergillus Differential Medium, on which Aspergillus flavus and Aspergillus parasiticus can be differentiated, no false positive colonies were to be seen.--On Malt Extract Agar with 7.5% NaCl the hydrophilic species were supressed, the xerophilic fungi were represented in greater number. The addition of 200 ppm rose bengal inhibited the growth of many fungi, but brought no rising of the colony count compared to Malt Extract Agar without rose bengal.--For the quantitive and qualitative mould plate count, Malt Extract Agar with 50 ppm Chloramphenicol and Chlortetracycline is recommended. For the detection of xerophilic moulds 7.5% NaCl should be added to that medium.--A proposition for the proceeding for the detection of moulds in foods is given.