Abstract Light emitting diodes of wavelength 410 nm were used to inactivate Listeria monocytogenes stains on paperboard, an increasingly popular food packaging material. The integrity of the cell membranes was examined using differential fluorescent staining. Scanning electron microscopy (SEM) was used to obtain a deeper understanding of L. monocytogenes stain formation on paperboard and the damage caused to the cells by the LEDs. While the planktonic L. monocytogenes population could be completely inactivated following a brief lag phase that lasted about 20 min, the illumination of the sessile population left some persisters despite immediate commencement of the inactivation. Planktonic populations of inocula sized 3, 5 and 7 log CFU/mL were reduced below the detection limit in 54, 80 and 84 min respectively, whereas it took 120 and 390 min to reach constancy in the sessile populations of inocula sized 5 and 7 log CFU/cm2. The number of membrane-damaged cells was seen to increase with the illumination time. SEM images provided evidence of the protection conferred by the stain on the underlying cells. This study demonstrates that blue LEDs have the potential to reduce the risk of L. monocytogenes contamination from paperboard cartons under refrigeration.

中文翻译：

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使用 410 nm 发光二极管灭活纸板（一种食品包装材料）上的单核细胞增生李斯特菌

摘要 波长 410 nm 的发光二极管用于灭活纸板上的单核细胞增生李斯特菌污渍，纸板是一种日益流行的食品包装材料。使用差异荧光染色检查细胞膜的完整性。使用扫描电子显微镜 (SEM) 更深入地了解纸板上单核细胞增生李斯特菌染色的形成以及 LED 对细胞造成的损害。虽然在持续约 20 分钟的短暂滞后期后，浮游单核细胞增生李斯特菌种群可以完全灭活，尽管灭活立即开始，但无柄种群的照明仍留下了一些持久性。3、5 和 7 log CFU/mL 接种物的浮游种群分别在 54、80 和 84 分钟内降至检测限以下，而在大小为 5 和 7 log CFU/cm2 的接种物的固着种群中达到恒定需要 120 和 390 分钟。观察到膜受损细胞的数量随着光照时间的增加而增加。SEM 图像提供了染色对底层细胞的保护作用的证据。这项研究表明，蓝色 LED 有可能降低冷藏条件下纸板箱被单核细胞增生李斯特菌污染的风险。