Abstract
PurposeWith the present work, we aimed to assess the occurrence of ochratoxigenic fungi and Ochratoxin A (OTA) in dried grapes from Tunisia.MethodsDried grapes samples (n = 90) were investigated for the presence of ochratoxigenic fungi, which were further characterized at the species level through amplification of the internal transcribed spacer (ITS) region and polymerase chain reaction (PCR) product sequencing. Fungal isolates were tested for their ochratoxigenic potential by high-performance liquid chromatography with fluorescence detection (HPLC-FLD), as well as dried grapes samples after an immunoaffinity column (IAC) clean-up procedure.ResultsBlack Aspergilli isolates were the dominant genre among the filamentous fungi found in dried grapes samples and were the only OTA-producing fungi encountered. Aspergillus niger aggregate were the most frequently found isolates reaching 70%, 80%, and 85% in dried grapes samples from regions of Kelibia, Sfax, and Rafraf, respectively, while covered 100% of the relevant mycobiota found in imported samples. Aspergillus carbonarius isolates were found only in Sfax’s and Kelibia’s samples, while uniseriate Aspergilli were found between 7 and 20% in dried grapes from Kelibia, Sfax, and the imported samples. The in vitro OTA production test showed that 88.9% of OTA-producing isolates belonged to A. carbonarius with OTA levels varying from 0.06 to 1.32 μg/g of Czapek Yeast Agar (CYA). The remaining OTA-producing fungi (11.1 %) belonged to A. niger aggregate group having a maximum OTA potential of 2.88 μg/g CYA, and no uniseriate Aspergilli isolate was able to produce OTA. All dried grapes samples were free of OTA presence.ConclusionAccording to the present study’s findings, no OTA contamination was recorded in the investigated samples from Tunisian market. Nevertheless, the presence of strong OTA producers A. carbonarius in samples originated from the two out of three studied Tunisian regions, as well the high incidences of Aspergillus niger aggregate group with an attested potential for OTA production in all samples, necessitates further research on Tunisian dried grapes. Additionally, a continuous analysis of staple food of the Mediterranean diet is imperative to insure the best quality for the consumers and prevent potential health problems.
Highlights
Vitis vinifera L. (Vitaceae) is a species of Vitis, native to the Mediterranean region (Fernandes et al 2013)
The effects of fungal growth in grapes lead to numerous effects such as the production of metabolites that may affect the organoleptic properties of grapes and derived products, and the production of toxic compounds namely Ochratoxin A (OTA) (Dachery et al 2019), which may be produced in vineyards by several fungal species such as Penicillium verrucosum in temperate climates and Aspergillus ochraceus and Aspergillus carbonarius in tropical and warm ones (Amézqueta et al 2012)
Several studies conducted in southern European countries had shown that other ochratoxigenic spp. like Aspergillus ochraceus was detected at very low incidences while Penicillium verrucosum was not isolated from grapes grown in warm climates (Pitt et al 2000; Covarelli et al 2012)
Summary
Vitis vinifera L. (Vitaceae) is a species of Vitis, native to the Mediterranean region (Fernandes et al 2013). The effects of fungal growth in grapes lead to numerous effects such as the production of metabolites that may affect the organoleptic properties of grapes and derived products, and the production of toxic compounds namely Ochratoxin A (OTA) (Dachery et al 2019), which may be produced in vineyards by several fungal species such as Penicillium verrucosum in temperate climates and Aspergillus ochraceus and Aspergillus carbonarius in tropical and warm ones (Amézqueta et al 2012) Such fungi can contaminate crops prior to harvest and more commonly during storage (EFSA 2006) and lead to the contamination of dried grapes, grape juices, and several types of wine (Welke 2019)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
