Journal zyxwvutsrq of Applied Bacteriology Symposium Supplement zyxwvuts 1989,27S-35S zyxwv Filamentous fungi in food and feed zy R. A. SAMSON Centraalbureau uoor Schimmelcultures, PO Box 273,3740 AG Baarn, The Netherlands 1. Introduction, 27s 2. Nomenclature and taxonomy of the filamentous fungi, 27s 2.1 Criteria for classification, 29s 3. Occurrence of food-borne fungi, 29s 4. Spoilage, 30s 4.1 Heat-resistant ascomycetes, 30s 4.2 Moulds resistant to preservatives, 32s 5. Conclusions, 33s 6. Acknowledgements, 33s 7. References, 33s 1. Introduction For many years our knowledge of the filamentous fungi in foods and feeds was poor. The extensive research on mycotoxins since their discovery in the 1960s has drawn attention to food mycology, but it is only recently that research has been focused on the biology of the fungi rather than on their chemistry. The importance of the filamentous fungi in food microbiology has now gained wider recognition. Books and manuals describing procedures for isolation and identification of food-borne fungi have become available (Pitt zyxwvuts & Hocking 1985; Beuchat 1987, Samson & Van Reenen-Hoekstra 1988). The systematics of the common food-borne fungi have now been improved considerably and with the exception of some genera the nomenclature of the taxa is now well accepted and stable. The efforts of international working groups studying the important genera of Penicillium, Aspergillus and Fusarium have stimulated discussions and in many cases reached consensus about species delimitations (see also Pitt, and Brayford, this publication). Another step forwards was the start of the discussion on general concepts in food mycology, such as media, isolation and enumeration (King et zyxw al. 1986). This paper reviews the state of art with the filamentous fungi. Two areas of recent spoilage prob- lems are discussed briefly. Aspects concerning techniques and mycotoxins will not be dealt with and the reader is referred to the other contributions in this publication. 2. Nomenclature and taxonomy of the filamentous fungi Beuchat (1985) stressed the importance of understanding both food mycology and taxonomy as they relate to food processing and preservation. For the quality control of food and feed, the identification of the contaminating mycoflora is essential. The identification to species level should provide impor- tant data about the biology and biochemistry of the organism, including the possible production of mycotoxins. At present the taxonomy of most food-borne genera is known, so identification to species level is possible. Samson et al. (1986) and Pitt & Hocking (1985)(see Table 1) have each listed the genera which occur in foods and feeds. There is a small difference between the two lists with respect to certain genera and this may be explained by deviation in geographical distribution (Australia vs. Europe) and in different concepts of food mycology. Samson & Van Reenen-Hoekstra (1988) described 96 species of the most common filamentous fungi with keys to the taxa. The taxonomy of the three important deuteromycete genera, Penicillium, Aspergillus and Fusarium is still in a state of flux. The nomenclature and species concepts in Penicillium and Aspergillus, however, have been improved, particularly by international co-operation (Samson & Pitt 1985). In