Jeon Min-Jin, Ha Jae-Won
Department of Food Science and Biotechnology, Global K-Food Research Center, Hankyong National University, Anseong-si, 17579, South Korea.
Department of Food Science and Biotechnology, Global K-Food Research Center, Hankyong National University, Anseong-si, 17579, South Korea.
Food Microbiol. 2020 Dec;92:103584. doi: 10.1016/j.fm.2020.103584. Epub 2020 Jun 30.
The objectives of this study were to evaluate the bactericidal effects of X-ray irradiation and gallic acid (GA) against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on lettuce leaves and in phosphate-buffered saline (PBS). Inoculated PBS and lettuce were exposed to X-rays (0.05, 0.1, and 0.15; 0.1, 0.2, and 0.3 kGy, respectively), and GA was applied to lettuce leaves as a solution and in PBS at concentrations of 0.5% (w/v). Combined treatment with 0.3 kGy and 0.5% GA reduced E. coli O157:H7, S. Typhimurium, and L. monocytogenes cell counts 5.41, 2.57, and 1.36 log CFU/cm on lettuce, respectively. Combined treatment with 0.15 kGy X-ray and 0.5% GA reduced counts for the same species by 6.54, 4.24, and 1.51 log CFU/mL in PBS. The combined treatments exerted a synergistic antibacterial effect against E. coli O157:H7 on lettuce, but not against S. Typhimurium or L. monocytogenes. In PBS, the synergistic effect was confirmed in both E. coli O157:H7 and S. Typhimurium cells. Mechanistic investigations indicated that the synergistic antibacterial effect was associated with intracellular reactive oxygen species (ROS) generation and bacterial cell membrane damage. Additionally, the X-ray and GA combination treatment did not adversely affect the color, total phenol content, and texture of lettuce. These findings demonstrate that treatment with X-ray radiation and GA can enhance the microbiological safety of fresh produce.
本研究的目的是评估X射线辐照和没食子酸（GA）对生菜叶片及磷酸盐缓冲盐水（PBS）中大肠杆菌O157:H7、鼠伤寒沙门氏菌和单核细胞增生李斯特菌的杀菌效果。将接种后的PBS和生菜分别暴露于X射线（分别为0.05、0.1和0.15；0.1、0.2和0.3千戈瑞），并将GA以0.5%（w/v）的浓度作为溶液施用于生菜叶片及PBS中。0.3千戈瑞和0.5% GA的联合处理使生菜上的大肠杆菌O157:H7、鼠伤寒沙门氏菌和单核细胞增生李斯特菌细胞计数分别减少5.41、2.57和1.36 log CFU/cm。0.15千戈瑞X射线和0.5% GA的联合处理使PBS中相同菌属的细胞计数分别减少6.54、4.24和1.51 log CFU/mL。联合处理对生菜上的大肠杆菌O157:H7产生了协同抗菌作用，但对鼠伤寒沙门氏菌或单核细胞增生李斯特菌没有作用。在PBS中，大肠杆菌O157:H7和鼠伤寒沙门氏菌细胞均证实有协同作用。机理研究表明，协同抗菌作用与细胞内活性氧（ROS）生成和细菌细胞膜损伤有关。此外，X射线和GA联合处理对生菜的颜色、总酚含量和质地没有不利影响。这些研究结果表明，X射线辐照和GA处理可以提高新鲜农产品的微生物安全性。
