Comparison between different sun drying methods for dried vine production in relation to Aspergillus section Nigri...

This study provides a comprehensive evaluation of three sun drying methods, gravel drying yard (GDY), drying on structure (DS), and drying on vine (DOV), in relation to the occurrence of Aspergillus section Nigri species and ochratoxin A (OTA) accumulation in dried vine fruits from San Juan, Argentina. Aspergillus section Nigri was detected in all samples in different percentages. Molecular identification revealed that Aspergillus section Nigri isolates were dominated by A. tubingensis within the A. niger aggregate, while all isolates of the A. carbonarius group were confirmed as A. carbonarius, with uniseriate species detected only rarely. Drying methods showed marked differences in fungal incidence and OTA accumulation. GDY exhibited the lowest incidence of A. carbonarius and minimal OTA levels, while DOV showed the highest OTA accumulation. A strong association between A. carbonarius incidence and OTA levels was observed across all methods. These differences were mainly explained by variations in maximum temperature and drying duration. GDY and DS reached higher temperatures and shorter drying times, limiting fungal growth, whereas DOV maintained temperatures within ranges favourable for OTA production over extended periods. Ochratoxin A was detected in 33% of samples at the end of storage. Although contamination frequency was lower than that reported in other countries, concentrations varied widely. Notably, the highest OTA levels were observed during the storage stage, indicating that this phase represents a critical point for toxin accumulation. These findings emphasise the critical role of storage conditions in OTA risk and inform improved safety management of dried vine fruit production.