Ochratoxin A (OTA) and ochratoxigenic fungi in grapes and wine in Argentina

PONSONE MARÍA LORENA; CHIOTTA MARIA LAURA; TORRES ADRIANA; COMBINA MARIANA; CHULZE SOFIA

Mendoza

Congreso; XI Congreso Latinoamericano De Viticultura Y Enología; 2007

ABSTRACT-RESUMEN.The aim of this work was to evaluate the fate of OTA during the main stages of the winemakingprocess from the vineyard to the winery, in order to identify possible CCPs and to establishcorrective actions. The evolution of contamination whit Aspergillus section Nigri and ochratoxin Aoccurrence was evaluated several vineyards located in Argentina during 2003-2004 ad 2006-2007. Bunches of grapes at different growth stages were collected, and berry samples wereplated on petri dishes containing dichloran 18% glycerol agar (DG18) and Dichloran RoseBengal Chloramphenicol agar (DRBC) media (Pitt and Hocking 1997). After an incubation periodof 7 days at 25 ºC ± 1 ºC, the mycoflora belonging to Aspergillus section Nigri was identified.The main species isolated belonged to A. niger aggregate. The OTA presence is beingevaluated in these grape samples. The vinification study was done using most from two varietiesof red grapes (Tempranillo and Bonarda) cultivated under two different cropping practices(organic and conventional). A set of four tanks (100 L each) per rape variety was establishedwith must from Bonarda and Tempranillo (conventional and organic) and inoculated with twoSaccharomyces strains: Saccharomyces bayanus (EC1118) and Saccharomyces cerevisiae(ICV D80). Ochratoxin A was added to the initial Tempranillo must in order to get an initialconcentration of about 6μg/L and for Bonarda musts of 0.3 μg/L . Samples were collected ondifferent periods through the process. OTA analysis was done according to Visconti et al (2001).The limit of detection was 0.05 ng ml-1 The OTA levels during the vinification dropped in averageabout 85%. The reduction in OTA concentration could be explained due to the fermentationprocess. Adsorption of the toxin to the yeasts lees could occur. The type of Saccharomycesstrain added showed no effect in the toxin reduction.