Modelling the growth of ochratoxigenic Aspergillus carbonarius isolated from Argentinean dried vine

A. PATRIARCA; S.M. ROMERO; G. VAAMONDE; A.J. RAMOS; S. MARÍN

Lleida

Congreso; International Congress of Postharvest Pathology; 2011

Aspergillus carbonarius is the major responsible for the ochratoxin A present in grape and its derivatives, such as wine and raisins. The purpose of the present study was to model the growth of ochratoxigenic strains of A. carbonarius under environmental conditions which may take place during postharvest and dehydration of grapes and validate those models with external literature data. Czapek Yeast Extract agar was adjusted to seven different water activities: 0.80, 0.825, 0.85, 0.87, 0.89, 0.925 and 0.95. Plates were incubated at 15, 20, 25, 30, and 35°C. Both kinetic and probability models were applied. No growth was observed at 0.80 aw. Growth data were fitted to the primary model of Baranyi and the maximum growth rates were modeled as a function of temperature and water activity by several kinetic secondary models. A cardinal model was the more suitable to describe the growth kinetics of A. carbonarius. The developed model was validated on independent data sets from the literature and presented acceptable goodness of prediction. A logistic regression polynomial model was applied to predict the probability of growth over time. The degree of agreement between predictions and observations was 91.3% concordant. Validation of the probability model with literature data sets showed high percentages of agreement. Results indicate that the developed predictive models could be satisfactorily employed to describe the combined effect of temperature and water activity on the growth of A. carbonarius under the experimental conditions.