Ochratoxin A-producing species in grapes and sun-dried grapes and their relation to ecophysiological factors

Abstract

Aims: To explain the dominance of OTA-producing fungal species in sun-dried grapes for special wine production through an ecophysiological approach. Methods and Results: Grapes at different ripening stages, sun-dried grapes and raisins were analysed for fungal presence, and isolates identified. Aspergillus section Nigri incidence in grapes increased with grape maturation. In the ecophysiological study five isolates (Alternaria alternata, Cladosporium herbarum, Penicillium decumbens, Aspergillus carbonarius, A. niger aggregate and A. section Nigri uniseriate) were inoculated in SNM medium at four a w (0AE82-0AE97) and incubated at 20, 30 and 40°C for 18 d. Isolates were also inoculated in pairs to evaluate fungal interactions recording their growth rates and indexes of dominance. Aspergillus section Nigri grew in a wider range of temperature and a w , had higher growth rates than the others under most of the conditions tested and showed behaviour usually dominant. Conclusions: The presence of A. section Nigri is predominant in grapes during harvesting and sun-drying period likely because of a better adaptation to hot and humid environment. Significance and Impact of the Study: The duration of the drying period should be reduced as much as possible without compromising the quality of the final product, or drying the grapes in controlled chambers with dry hot air flow.

Mycotoxins in botanicals and dried fruits: A review

“…Aspergillus carbonarius was the predominant fungal source of OTA in dried vine fruits examined in Spain and Argentina (Abarca et al 2003;Magnoli et al 2004;Valero et al 2005). Other OTA-producing fungi which have been isolated from grapes or dried vine fruit and are probable contributors to its presence in dried vine fruits include A. niger var.…”

The effect of dipping pretreatment on ochratoxin A accumulation in sultanas and currants

“…The maximum level of OTA allowed in dried vine fruits in Europe is 10 µg/kg (12). Moreover, Aspergillus niger aggregate and Aspergillus carbonarius have been blamed as the OTA producers in grape and grape-derivatives (13)(14)(15). Astoreca et al (16) reported that, throughout the grape drying process, the biodiversity index showed a decreasing trend because the water activity (Aw) of grape was decreasing and the sugar level was increasing.…”

Mycotoxin-Producing Penicillium and Other Fungi Isolated From Slovak Wine Grapes at Various Stages of Maturation

“…and Rhizopus spp. These genus are regarded as the main natural contaminants of grapes (Valero et al, 2005). Changes in the total fungal population over the growing season have been observed.…”