Monitoring Pilot-Scale Ultrasound Treatment of the Removal of Pesticide Residues from Fresh Zucchinis Using 2D and 3D Front-Face Fluorescence Spectroscopy

The removals of boscalid and pyraclostrobin residues from zucchinis by ultrasonic treatment were investigated at the laboratory and pilot scales (40 L) in this study. 2D and 3D front-face fluorescence spectroscopy (FFFS) coupled with parallel factor analysis (PARAFAC) was used to monitor the quality of the collected ultrasonic cleaning water and the efficiency of the ultrasonic treatment applied on the zucchinis. For the 3D FFFS analysis, two-PARAFAC component model was validated. The relative concentration of boscalid stalled in the cleaning water increased by fivefold when a comparison is done between the use of ultrasonication and the immersion without ultrasound technique. The highest removal levels for boscalid and pyraclostrobin were observed after 10 and 50 min of ultrasonication at the laboratory scale and after 15 and 15 min at the pilot scale, respectively. Afterwards, the removal rates seem to decrease with the time for the two pesticide residues. The kinetic of removal rates was fitted with a logarithmic model with R² = 0.9469 for the boscalid and R² = 0.9356 for the pyraclostrobin. In conclusion, this study showed the significant potential of FFFS specifically fluorescence EEM coupled with PARAFAC for at-line and/or off-line routine analysis of PRs in the framework of the application of ultrasound treatment for the zucchini cleaning at the pilot scale.