PDF(Pubmed)
Abstract：
Controlling Salmonella 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/cm2) and 460 nm (614.9 mW/cm2), was evaluated against a five-serovar cocktail of Salmonella enterica 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/cm2. 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 Salmonella cells and the temperature changes on SS surfaces were also measured. The treatment energy dose had a significant effect on Salmonella inactivation levels. On clean SS surfaces, the reduction in Salmonella counts ranged from 0.8 to 7.4 log CFU/cm2, while, on soiled coupons, the inactivation levels varied from 1.2 to 4.2 log CFU/cm2. Blue LED treatments triggered a significant generation of ROS within Salmonella cells, as well as a substantial temperature increase in SS surfaces. However, in the presence of organic matter, the oxidative stress in Salmonella cells declined significantly, and treatments with higher energy doses (>700 J/cm2) 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.
摘要：
控制干燥食品加工环境中的沙门氏菌污染是一项重大挑战，因为它们对干燥应力的耐受性和增强的耐热性。蓝光正在成为用于表面去污的紫外线照射的更安全的替代品。在本研究中,超高辐照度（UHI）蓝光的抗菌功效，由发光二极管（LED）在405nm（841.6mW/cm2）和460nm（614.9mW/cm2）的波长下产生，在清洁和污染的不锈钢（SS）表面上，针对肠道沙门氏菌干细胞的五血清型混合物进行了评估。在221至1106焦耳/平方厘米的等效能量剂量下对接种的试样进行蓝光照射处理。小麦粉用作模型食物土壤系统。为了确定蓝光的杀菌机制，还测量了沙门氏菌细胞中活性氧（ROS）的细胞内浓度以及SS表面的温度变化。处理能量剂量对沙门氏菌灭活水平有显著影响。在干净的SS表面,沙门氏菌计数的减少范围为0.8至7.4logCFU/cm2，而，在弄脏的优惠券上，失活水平从1.2到4.2logCFU/cm2不等。蓝光LED治疗引发了沙门氏菌细胞内ROS的大量产生，以及SS表面的温度大幅增加。然而,在有机物的存在下，沙门氏菌细胞的氧化应激显著下降,并且需要更高能量剂量(>700J/cm2)的治疗以维持在清洁SS上观察到的抗微生物效力。UHI蓝光LED处理的杀菌效果的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可以代表一种新的成本和时间有效的替代方案，用于控制干燥食品加工环境中的微生物污染。
