Lin Chia-Min, Hsiao Chun-Ping, Lin Hong-Siou, Liou Jian Sin, Hsieh Chang-Wei, Wu Jong-Shinn, Hou Chih-Yao
Department of Seafood Science, National Kaohsiung University of Science and Technology, Kaohsiung 811, Taiwan.
Department of Mechanical Engineering, National Chiao Tung University, Hsinchu 300, Taiwan.
Foods. 2020 Oct 19;9(10):1491. doi: 10.3390/foods9101491.
Eggs are one of the most commonly consumed food items. Currently, chlorine washing is the most common method used to sanitize shell eggs. However, chlorine could react with organic matters to form a potential carcinogen, trihalomethanes, which can have a negative impact on human health. Plasma-activated water (PAW) has been demonstrated to inactivate microorganisms effectively without compromising the sensory qualities of shell eggs. For this study, various amounts (250, 500, 750, or 1000 mL) of PAW were generated by using one or two plasma jet(s) at 60 watts for 20 min with an air flow rate at 6 or 10 standard liters per minute (slm). After being inoculated with 7.0 log CFU Enteritidis, one shell egg was placed into PAW for 30, 60, or 90 s with 1 or 2 acting plasma jet(s). When 2 plasma jets were used in a large amount of water (1000 mL), populations of . Enteritidis were reduced from 7.92 log CFU/egg to 2.84 CFU/egg after 60 s of treatment. In addition, concentrations of ozone, hydrogen peroxide, nitrate, and nitrite in the PAW were correlated with the levels of antibacterial efficacy. The highest concentrations of ozone (1.22 ppm) and nitrate (55.5 ppm) were obtained with a larger water amount and lower air flow rate. High oxidation reduction potential (ORP) and low pH values were obtained with longer activation time, more plasma jet, and a lower air flow rate. Electron paramagnetic resonance (EPR) analyses demonstrated that reactive oxygen species (ROS) were generated in the PAW. The observation under the scanning electron microscope (SEM) revealed that bacterial cells were swollen, or even erupted after treatment with PAW. These results indicate that the bacterial cells lost control of cell permeability after the PAW treatment. This study shows that PAW is effective against S. Enteritidis on shell eggs in a large amount of water. Ozone, nitrate, and ROS could be the main causes for the inactivation of bacterial cells.
鸡蛋是最常食用的食品之一。目前，氯洗是用于清洁带壳鸡蛋的最常见方法。然而，氯可能与有机物发生反应，形成潜在致癌物三卤甲烷，这可能对人体健康产生负面影响。已证明等离子体活化水（PAW）能有效灭活微生物，同时不影响带壳鸡蛋的感官品质。在本研究中，使用一个或两个等离子体射流，以60瓦功率运行20分钟，空气流速为6或10标准升每分钟（slm），产生不同量（250、500、750或1000毫升）的PAW。在接种7.0 log CFU肠炎沙门氏菌后，将一枚带壳鸡蛋放入PAW中，使用1个或2个作用的等离子体射流处理30、60或90秒。当在大量水（1000毫升）中使用2个等离子体射流时，处理60秒后，肠炎沙门氏菌的数量从7.92 log CFU/枚降至2.84 CFU/枚。此外，PAW中臭氧、过氧化氢、硝酸盐和亚硝酸盐的浓度与抗菌效果水平相关。在水量较大且空气流速较低的情况下，臭氧（1.22 ppm）和硝酸盐（55.5 ppm）的浓度最高。激活时间越长、等离子体射流越多且空气流速越低，氧化还原电位（ORP）越高，pH值越低。电子顺磁共振（EPR）分析表明，PAW中产生了活性氧物种（ROS）。扫描电子显微镜（SEM）观察显示，用PAW处理后，细菌细胞肿胀，甚至破裂。这些结果表明，PAW处理后细菌细胞失去了对细胞通透性的控制。本研究表明，PAW在大量水中对带壳鸡蛋上的肠炎沙门氏菌有效。臭氧、硝酸盐和ROS可能是细菌细胞失活的主要原因。
