Mycotoxin formation in hulless barley during granary storage at 15 and 19% moisture content

Abstract

Eleven-kilogram parcels of hulless barley ( Hordeum vulgare L. cv. Condor) at 15 and 19% initial moisture content were kept in simulated storage in a Manitoba farm granary for 20 weeks (June 1996–October 1996) to determine biotic and abiotic changes and mycotoxin production. Temperature, moisture content, CO 2 levels, ergosterol content, seed germination, microfloral infection, and the presence of major mycotoxins were monitored. Ochratoxin A, citrinin and sterigmatocystin reached mean levels of 24, 38 and 411 ppb by 20 weeks in the 19% moisture content barley, but were absent in the 15% moisture content barley; no other mycotoxins were detected. Penicillium species and Aspergillus versicolor (Vuill.) Tiraboschi comprised the predominant microflora. The effect of storage time was apparent at both 15 and 19% moisture content for grain temperature, Alternaria alternata (Fr.) Keissler, Penicillium species and Aspergillus versicolor. At 19% moisture content, storage time also affected moisture content, CO 2 level, ergosterol content, seed germination, and mycotoxin production. At 19% moisture content, elevated ergosterol levels at weeks 4 and 8 appear to offer early warning of the appearance of sterigmatocystin at week 12, and of ochratoxin A and citrinin at week 20.