Enhancement of UVC-light treatment of tangerine and grapefruit juices through ultrasonic atomization

- Ultrasonic atomization of tested juices improved UVC inactivation of S. cerevisiae.
- Combining these technologies did not adversely affect the juices' quality parameters.
- Tested UVC arrangements significantly affected yeast inactivation.
- Distance from the UVC lamp to the sprayed juice strongly affected yeast inactivation.

The objective of the study was to combine shortwave ultraviolet irradiation (UVC-Light) with ultrasonic atomization (UA) to generate microdroplets by atomizing the juices to enhance contact with UVC-Light and to evaluate its effect on the inactivation of Saccharomyces cerevisiae as well as on selected physicochemical parameters of tangerine and grapefruit juices. UVC lamps and an ultrasonic atomizer were used individually and in combination. The effect of lamps' orientation (horizontal or vertical) and the number of lamps (1 or 2) were assessed. No significant (p > 0.05) changes on pH, °Bx, and color of studied juices were observed, since the contact time of the microdroplets with the UVC-Light was short. After processing 250 mL of juice, microbial population was reduced by 0.84 log cycles when using a single UVC lamp combined with UA while a 2.8 log cycles reduction was observed after three passes. Tested configurations with two lamps did not achieve effective inactivation of S. cerevisiae, possibly because the generated microdroplets were not in close contact with UVC-light as was the case with one lamp.Industrial relevanceThe ultrasonic atomization for the UVC-treatment of juices was assessed for the first time in this work. The ultrasonic atomization of juices may be suitable for the inactivation of yeasts when combined with UVC-Light as long as atomization takes place near the irradiation site. These combined technologies have the potential to generate foods minimally processed.