Ochratoxin A (OTA) is a fungal secondary metabolite produced by Aspergillus and Penicillium species. It has been detected in a wide range of commodities, including cereals, coffee, grapes, raisins, must and wine. Within grape derivative products, the raisins, red wine and sweet wines have reported to contain the highest OTA levels. Aspergillus section Nigri (A. niger and A. carbonarius) are considered the OTA source in these commodities and they are commonly isolated among other fungi from grapes and raisins.Starting from this basis the objectives of this thesis were focused into three main aspects: (1) Evaluation of the food products: vine dried fruits and special wines, concerning the mycobiota and OTA occurrence and incidence; (2) Ecophysiological studies of the ochratoxigenic fungi and accompanying mycobiota as affected by environmental conditions; (3) Control and preventive methods such as the evaluation of residual activity of pre-harvest fungicides during grape dehydration and the use of modified atmospheres.Wine origin and winemaking procedure showed to be determinant for the final OTA content. All special wines analysed from northern European regions were negative for OTA while more than 50% of wines from warmer regions were positive for OTA contamination. The wines with higher OTA levels were fortified musts followed by those made from dried grapes. Acoholic and malo-lactic fermentations, biological 'crianza' (Flor yeast) and the action of Botrytis cinerea in noble rot of grapes may diminish the OTA levels in wine.In grapes, the presence of Aspergillus section Nigri became predominant at harvest and mainly during sun-drying. Prevalence of Aspergillus section Nigri can be explained by their adaptation to environmental conditions of sun-drying, and by their ability to dominate other fungal species involved when coming into contact with them. Among the Aspergillus section Nigri, A. niger aggregate was dominant, although A. carbonarius increased its inci
| Identifer | oai:union.ndltd.org:TDX_UDL/oai:www.tdx.cat:10803/8384 |
| Date | 13 July 2007 |
| Creators | Valero Rello, Ana |
| Contributors | Sanchís Almenar, Vicente, Universitat de Lleida. Departament de Tecnologia d'Aliments |
| Publisher | Universitat de Lleida |
| Source Sets | Universitat de Lleida |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/doctoralThesis, info:eu-repo/semantics/publishedVersion |
| Format | application/pdf |
| Source | TDX (Tesis Doctorals en Xarxa) |
| Rights | info:eu-repo/semantics/openAccess, ADVERTIMENT. L'accés als continguts d'aquesta tesi doctoral i la seva utilització ha de respectar els drets de la persona autora. Pot ser utilitzada per a consulta o estudi personal, així com en activitats o materials d'investigació i docència en els termes establerts a l'art. 32 del Text Refós de la Llei de Propietat Intel·lectual (RDL 1/1996). Per altres utilitzacions es requereix l'autorització prèvia i expressa de la persona autora. En qualsevol cas, en la utilització dels seus continguts caldrà indicar de forma clara el nom i cognoms de la persona autora i el títol de la tesi doctoral. No s'autoritza la seva reproducció o altres formes d'explotació efectuades amb finalitats de lucre ni la seva comunicació pública des d'un lloc aliè al servei TDX. Tampoc s'autoritza la presentació del seu contingut en una finestra o marc aliè a TDX (framing). Aquesta reserva de drets afecta tant als continguts de la tesi com als seus resums i índexs. |
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