Evaluation of an In-Packing Line Far-UVC Light System for Reducing Natural Microflora and Escherichia coli  on Apple Surfaces

Recalls and outbreaks associated with apples, particularly related to postharvest handling, have pushed the industry to continually investigate microbial control techniques. Far-UVC radiation (UVC with shorter wavelengths) has potential for microbial inactivation with low risks to human health. This study was conducted to evaluate the efficacy of a far-UVC system (krypton chloride excimer lamp with peak emission of 222 nm) integrated into a packing line for reducing background microflora levels and artificially inoculated Escherichia coli on apple surfaces. Four far-UVC lights were previously installed in a two-by-two pattern on an apple packing line following spray bar sanitation. Two trials were conducted with 15 apples per treatment, assessing microbial levels before and after far-UVC treatment for 5 or 10 s at 0.3 m from apples on a roller bed. The light intensity above the roller beds was 237 μW/cm2. Far-UVC treatment resulted in significant decreases in aerobic plate counts, total coliforms, yeasts, molds, and E. coli of 0.6, 0.6, 0.5, 0.9, and 0.7 log CFU per apple, respectively, indicating the potential for this treatment to enhance apple quality and serve as part of a hurdle approach for safety. Optimization and further research are warranted to fully harness the benefits of far-UVC technology for the apple industry.