Department of Food Science and Biotechnology, College of Engineering, Global K-Food Research Center, Hankyong National University, Anseong-si, 17579, South Korea.
Department of Food Science and Biotechnology, College of Engineering, Global K-Food Research Center, Hankyong National University, Anseong-si, 17579, South Korea.
Food Microbiol. 2019 Dec;84:103277. doi: 10.1016/j.fm.2019.103277. Epub 2019 Jul 22.
The purpose of this study was to evaluate the synergistic bactericidal efficacy of combining ultrasound (US) and fumaric acid (FA) treatment against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in apple juice and to identify the synergistic bactericidal mechanisms. Additionally, the effect of combination treatment on juice quality was determined by measuring the changes in color, pH, non-enzymatic browning index, and total phenolic content. A mixed cocktail of the three pathogens was inoculated into apple juice, followed by treatment with US (40 kHz) alone, FA (0.05, 0.1, and 0.15%) alone, and a combination of US and FA for 1, 2, 3, 4, and 5 min. Combined US and 0.15% FA treatment for 5 min achieved 5.67, 6.35, and 3.47 log reductions in E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively, with the 1.55, 2.37, and 0.57 log CFU reductions attributed to the synergistic effect. Although the pH value slightly decreased as FA increased, there were no significant (P > 0.05) differences in color values, browning indices, and phenolic content between untreated and treated samples. To identify the mechanism of this synergistic bactericidal action, membrane integrity, malfunctions in the membrane efflux pump, and intracellular enzyme activity were measured. The analyses confirmed that damage to the cell envelope (membrane integrity and efflux pump) was strongly related to the synergistic microbial inactivation. These results suggest that simultaneous application of US treatment and FA is a novel method for ensuring the microbial safety of apple juice.
本研究旨在评估超声（US）和富马酸（FA）联合处理对苹果汁中大肠杆菌 O157:H7、鼠伤寒沙门氏菌和单增李斯特菌的协同杀菌效果，并确定协同杀菌机制。此外，通过测量颜色、pH 值、非酶褐变指数和总酚含量的变化来确定组合处理对果汁质量的影响。将三种病原体的混合混合物接种到苹果汁中，然后单独用 US（40 kHz）、FA（0.05、0.1 和 0.15%）处理 1、2、3、4 和 5 分钟。联合 US 和 0.15% FA 处理 5 分钟，可使大肠杆菌 O157:H7、鼠伤寒沙门氏菌和单增李斯特菌分别减少 5.67、6.35 和 3.47 log，协同效应分别减少 1.55、2.37 和 0.57 log CFU。尽管随着 FA 的增加 pH 值略有下降，但未处理和处理样品之间的颜色值、褐变指数和酚含量没有显着差异（P > 0.05）。为了确定这种协同杀菌作用的机制，测量了膜完整性、膜外排泵故障和细胞内酶活性。分析证实，细胞膜完整性和外排泵的损伤与协同微生物失活密切相关。这些结果表明，同时应用 US 处理和 FA 是确保苹果汁微生物安全的一种新方法。
