Occurrence of fruit rot fungi (Aspergillus section Nigri) on some drying varieties of irrigated grapes

• Autores: J. I. Pitt, Ailsa D. Hocking, Su-Lin L. Leong
• Localización: Australian journal of grape and wine research, ISSN 1322-7130, Vol. 10, Nº 1, 2004, págs. 83-88
• Idioma: inglés
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• Dialnet Métricas: 1 Cita
• Resumen

  • The occurrence of Aspergillus section Nigr on certain varieties of grapes used for dried vine fruit (and especially on Sultana), was surveyed extensively during three harvest seasons (1998, 1999 and 2000). Members of Aspergillus section Nigr were enumerated and identified in a total of 806 samples comprising both fresh fruit as well as partially-dried and fully-dried grapes. Aspergillus aculeatus, A. carbonarius and A. niger were commonly isolated. Of those three species, A. niger showed the highest optimum temperature for growth, as well as highest thermal tolerance. That combination of properties probably accounts for the occurrence of A. niger in over 80% of fruit samples in all three seasons. A. carbonarius was also prevalent on fruit surveyed for fungal rots. Severity of infection with this group of fungi was highest in the seasons when grape berries were rain-damaged. Typically, the Aspergillus count increased during the initial stages of drying. Growth of these moulds while grapes are either still on the vine or during drying carries important implications for human consumption due to the potential for certain strains of these fungi to produce ochratoxin A. Fungal cultures on coconut cream agar plates were screened for production of ochratoxin A via fluorescence emission under UV light. Such fluorescence was observed in all isolates of A. carbonarius, but was not observed in any isolates of either A. aculeatus or A. niger.