Fungal infection and mycotoxic contamination of commercial maize.
Viljoen, J. H.; Marasas, W. F. O.; Thiel, P. G.;
Technical Communication - Department of Agricultural Development, South Africa Year: 1994 Issue: No. 238 Pages: 26-37 Ref: 2 ref.
1994
บทคัดย่อ
ABSTRACT :
Over several years the Maize Board has monitored the occurrence of fungal infection and mycotoxin contamination in commercial maize. At first, a multi-mycotoxin technique was employed (University of Natal). This showed that South African maize is relatively free of mycotoxins such as patulin, citrinin, aflatoxins, kojic, acid, ochratoxin, penicillic acid, sterigmatocystin, zearalenone and some trichothecenes. In 1989, analyses for specific mycotoxins were carried out (Medical Research Council, MRC) and the occurrence of the most important fungi was monitored (MRC and Maize Board). The mycotoxins involved were aflatoxins, zearalenone, deoxynivalenol [vomitoxin], nivalenol, moniliformin and fumonisins B1 and B2. The fungi monitored were Fusarium graminearum [Gibberella zeae], F. subglutinans [G. fujikuroi var. subglutinans], F. moniliforme [G. fujikuroi], Aspergillus flavus, Penicillium spp., Diplodia maydis [Stenocarpella maydis] and D. macrospora [S. macrospora]. The results showed that South Af
rican maize is virtually free of aflatoxins. The incidence of most other mycotoxins was very low and generally they occurred at levels far below those that could cause problems to consumers. Fumonisins were found frequently, but at low levels. A small number of white maize samples from Natal and the Northern Orange Free State contained fumonisins at levels approaching the lower levels of the range where problems associated with fumonisins were experienced in livestock. The levels of mycotoxins in maize products were markedly lower than in unprocessed grain. The levels decreased with the degree of refinement. The toxicology of fumonisins has not yet been fully studied, but it seems likely that max. tolerance limits for fumonisins, similar to those for alfatoxins, will be set in future. A study of the incidence of various fungi on some maize cultivars has shown a marked difference in the susceptibility of cultivars for various pathogens, including G. fujikuroi, the most important producer of fumonisins in maiz
e. It is concluded that the best solution to prevent the occurrence of harmful mycotoxins in cereal foods is the propagation of cultivars more tolerant of the causative pathogens.