Ultraviolet-C light (254 nm) treatment using a batch-style powder redistribution system for the inactivation of Salmonella surrogate, Enterococcus faecium, in wheat flour

Abstract

This study investigated the effect of enhanced 254 nm ultraviolet-C (UV-C) light exposure on the inactivation of Enterococcus faecium within wheat flour. The in vitro susceptibility of E. faecium on agar plates to UV-C light was determined before performing food studies. The results show significant reduction capacity, achieving an 8.7 ± 0.2 log reduction after 2.48 J/cm² of exposure. To determine the effect of enhanced UV exposure on wheat flour decontamination, four redistribution methods were compared based on their inactivation capacity potential. This included no redistribution, manual redistribution, and vibrating continuous redistribution on a novel system using two different sample containers: a Petri plate and a weighing boat. The most effective redistribution method was the continuous redistribution system with a weighing boat base, achieving a 4.1 log reduction in wheat flour after 7.43 J/cm² of exposure. The reduction capacity was further improved through sample size minimization. Reducing the treatment sample size from 1.00 g to 0.15 g minimized layering and improved the E. faecium reduction in wheat flour from 2.0 log in the 1.00 g sample to 3.6 log in the 0.15 g samples after treatment with a dosage of 2.48 J/cm². Theoretical adjusted fluence calculations support the need for powdered sample minimization for increased UV exposure, estimating that the 0.15 g wheat flour sample received a dosage approximately 6.66 times greater than the 1.00 g sample. Further optimization of exposure methods through system industrialization could improve on this study's results and accelerate its potential incorporation into powdered food processing.