AFLA-pistachio: development of a mechanistic model to predict aflatoxin contamination of greek pistachio nuts

Pistachios are cultivated worldwide for their high nutritional value and their good flavour. In Greece, the main pistachio variety is Pistachia vera cv Aegina. One of the main regions of pistachio cultivation in Greece is Aegina Island, located close to Athens and the pistachio nuts cultivated there are registered as P.D.O. (Product of Designation of Origin). During the last decades, several surveys on Greek pistachio nuts indicated high contamination with aflatoxin B1 (AFB1), therefore, aflatoxins are considered a major problem for the crop. In Europe, a legislation is in force and 12 μg/kg of AFB1 is the fixed limit. The ultimate goal of the current study was to develop a mechanistic, weather-driven model, to predict Aspergillus flavus growth and AFB1 contamination in pistachios on a daily base from nut setting until harvest. The planned steps were: i) to develop a prototype model based on AFLA-maize (Battilani et al., 2013), ii) to collect meteorological and AF contamination data in Aegina, iii) to run the model and elaborate a probability function to estimate the likelihood to overcome the legal limit and iv) to manage a preliminary validation. AFLA-pistachio model was developed; the validation was carried out using data collected in 2014 and 2015 as model input and around 70% of pistachio orchards were correctly classified by the model in respect to the legal limit. Results were very promising and AFLA-pistachio model seems to be a useful tool for stakeholders to follow the dynamic of AFB1 contamination risk throughout the pistachio growing season.