Comparison of 254 and 222 nm Ultraviolet-C Light for Treatment of Wheat Flour and Infant Formula: Antimicrobial Capacity, Color Analysis, and Light Energy Efficiency

Abstract

This study investigated the efficacy of ultraviolet-C (UV-C) light at 254 and 222 nm for inactivating Enterococcus faecium in wheat flour and powdered infant formula using a novel redistribution system to enhance particle exposure. The effects of varying UV-C dosages (0, 0.50, 1.24, and 2.48 J/cm²) on microbial reduction and color changes were evaluated. Results demonstrated that 254 nm UV-C light was more effective than 222 nm UV-C for decontaminating the product, achieving significantly greater reductions in E. faecium across both food matrices (p < 0.05). In wheat flour, 254 nm treatment achieved a 4.5-log reduction at 2.48 J/cm², compared to a 2.4-log reduction at 222 nm. In infant formula, the 254 nm treatment achieved a 3.5-log reduction, whereas the 222 nm treatment achieved a 1.5-log reduction. While 254 nm light showed greater inactivation capacity, the electrical energy required per log reduction was comparable between the two wavelengths (p < 0.05). Posttreatment CIELAB color analysis found that no visibly discernible color changes occurred in wheat flour or infant formula samples (p > 0.05). This study suggests that UV-C treatment, particularly at 254 nm, is a promising nonthermal decontamination method for powdered foods. It offers a potential energy-efficient solution to enhance their safety without significantly impacting visual quality.