Ana Valero

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

Aims:  To explain the dominance of OTA‐producing fungal species in sun‐dried grapes for special wine production through an ecophysiological approach.

Survey: Ochratoxin A in European special wines

The occurrence of Ochratoxin A (OTA) was examined in 121 special wines made using different winemaking techniques and from many European origins. The wine groups with the highest OTA content and occurrence, above 90%, were those were the must was fortified before fermentation (mean: 4.48μg/l) and those made from grapes dried by means of sun exposure (mean: 2.77μg/l). Fortified wines with long aging in wooden casks were about 50% contaminated, with OTA levels below 1.00μg/l. Wines affected by noble rot, late harvest wines and ice wines did not contain OTA. Overall, 19.8% of the wines studied contained OTA levels above the maximum permissible limit for the European Union (2μg/kg) in wine (excluding liqueur wines).

Effect of germicidal UVC light on fungi isolated from grapes and raisins

Aims:  To examine how UVC affects the different genera of fungi commonly isolated from grapes, with the aim of understanding changes in mycobiota during grape ripening and possible applications for preventing grape decay during storage.

Water Activity and Temperature Effects on Fungal Growth and Ochratoxin A Production by Ochratoxigenic Aspergillus carbonarius Isolated from Tunisian Grapes

This study investigated the effects of temperature (15 to 37 degrees C) and water activity (0.90 to 0.99) on the growth and production of ochratoxin A (OTA) by Aspergillus carbonarius cultured on synthetic nutrient medium (SNM) after 5 and 10 d of incubation. Total of 8 ochratoxigenic A. carbonarius, isolated from vineyards located in different regions of Tunisia, were used. Growth data were modeled by the flexible model of Baranyi and growth rates at each set of conditions were obtained. For both growth and OTA production, optimal water activity was 0.99; however, optimal temperature varied. The optimal temperature for growth was 30 degrees C. At 37 degrees C, the growth rate decreased significantly (P < 0.05). Maximum toxin production occurred at temperatures in the range of 15 to 25 degrees C with the optimum one depending on the isolate tested. Significant amounts of OTA were produced after only 5 d of incubation. Our results showed that A. carbonarius isolated from Tunisian grapes behave as those from European and Australian grapes, as reported in the literature, although some differences in trends for growth and OTA production were observed.

Effect of preharvest fungicides and interacting fungi on Aspergillus carbonarius growth and ochratoxin A synthesis in dehydrating grapes

Aims:  To evaluate the effect of preharvest grape pesticides in Aspergillus section Nigri infection in dehydrating grapes and the final ochratoxin A (OTA) content. Additionally, the effect of coinoculation of moulds frequently isolated from grapes and raisins on Aspergillus section Nigri infection was studied.

Mycelial growth and ochratoxin A production by Aspergillus section Nigri on simulated grape medium in modified atmospheres

Aims:  To evaluate the impact of modified atmosphere packaging on in vitro growth of Aspergillus carbonarius and Aspergillus niger, and possible effects on ochratoxin A (OTA) biosynthesis.

Brief in vitro study on Botrytis cinerea and Aspergillus carbonarius regarding growth and ochratoxin A

Aims:  To evaluate the effect of Botrytis cinerea growth on ochratoxin A (OTA) production by Aspergillus carbonarius and degradation.