On the application of respirometric system on hazelnut samples to predict aflatoxin production

In the present work, the correlation between the respirometric activity and the aflatoxin synthesis of the hazelnut microbiota has been investigated. Microcosms containing a monolayer of hazelnuts were maintained at controlled conditions in terms of temperature and humidity. To monitor microbial growth, CO2 was evaluated along with the specific O2 uptake rate, RO2, measured by a respirometric sensor, usually applied in the evaluation of soil microbial activity. The respiratory quotient (RQ) was calculated and a linear relationship between RQ and produced aflatoxins was obtained. Depending on incubation time, four main clusters of RQ values were identified: for higher incubation time (15–40 days) RQ was lower than 2 and an aflatoxin amount of 0.31–0.35 μg/kg was observed. CO2, O2, and aflatoxin data have been used to develop an autoregressive model and excellent agreement between measurements and estimations was obtained. In most cases, an error lower than 1% on the estimated value of the mycotoxin amount revealed the accuracy of the evaluation of the RQ. The present work represents the first attempt to develop an effective method, fast and low-cost, for the in-line monitoring of mycotoxin contamination.