Minor Martha, Sabillón Luis
Department of Family & Consumer Sciences, New Mexico State University, Las Cruces, NM 88003, USA.
Center of Excellence in Sustainable Food and Agricultural Systems, New Mexico State University, Las Cruces, NM 88003, USA.
Microorganisms. 2024 Jan 4;12(1):103. doi: 10.3390/microorganisms12010103.
Controlling contamination in dry food processing environments represents a significant challenge due to their tolerance to desiccation stress and enhanced thermal resistance. Blue light is emerging as a safer alternative to UV irradiation for surface decontamination. In the present study, the antimicrobial efficacy of ultra-high irradiance (UHI) blue light, generated by light-emitting diodes (LEDs) at wavelengths of 405 nm (841.6 mW/cm) and 460 nm (614.9 mW/cm), was evaluated against a five-serovar cocktail of dry cells on clean and soiled stainless steel (SS) surfaces. Inoculated coupons were subjected to blue light irradiation treatments at equivalent energy doses ranging from 221 to 1106 J/cm. Wheat flour was used as a model food soil system. To determine the bactericidal mechanisms of blue light, the intracellular concentration of reactive oxygen species (ROS) in cells and the temperature changes on SS surfaces were also measured. The treatment energy dose had a significant effect on inactivation levels. On clean SS surfaces, the reduction in counts ranged from 0.8 to 7.4 log CFU/cm, while, on soiled coupons, the inactivation levels varied from 1.2 to 4.2 log CFU/cm. Blue LED treatments triggered a significant generation of ROS within cells, as well as a substantial temperature increase in SS surfaces. However, in the presence of organic matter, the oxidative stress in cells declined significantly, and treatments with higher energy doses (>700 J/cm) were required to uphold the antimicrobial effectiveness observed on clean SS. The mechanism of the bactericidal effect of UHI blue LED treatments is likely to be a combination of photothermal and photochemical effects. These results indicate that LEDs emitting UHI blue light could represent a novel cost- and time-effective alternative for controlling microbial contamination in dry food processing environments.
由于其对干燥胁迫的耐受性和增强的耐热性，控制干食品加工环境中的污染是一项重大挑战。蓝光正在成为一种比紫外线照射更安全的表面去污替代方法。在本研究中，评估了由发光二极管（LED）产生的波长为405nm（841.6mW/cm）和460nm（614.9mW/cm）的超高辐照度（UHI）蓝光对清洁和污染的不锈钢（SS）表面上的五种血清型混合干燥细胞的抗菌效果。对接种的试片进行了能量剂量等效范围为221至1106J/cm的蓝光照射处理。小麦粉用作模拟食品污染系统。为了确定蓝光的杀菌机制，还测量了细胞内活性氧（ROS）的浓度以及SS表面的温度变化。处理能量剂量对灭活水平有显著影响。在清洁的SS表面上，菌落数减少范围为0.8至7.4 log CFU/cm，而在污染的试片上，灭活水平在1.2至4.2 log CFU/cm之间变化。蓝色LED处理引发细胞内ROS的大量产生以及SS表面温度的大幅升高。然而，在存在有机物的情况下，细胞内的氧化应激显著下降，需要更高能量剂量（>700J/cm）的处理才能维持在清洁SS上观察到的抗菌效果。UHI蓝色LED处理的杀菌作用机制可能是光热和光化学效应的组合。这些结果表明，发射UHI蓝光的LED可能是控制干食品加工环境中微生物污染的一种新型经济高效的替代方法。
