Department of Food and Animal Biotechnology, School of Agricultural Biotechnology, Seoul National University, Seoul, South Korea.
Int J Food Microbiol. 2012 Jul 2;157(2):218-23. doi: 10.1016/j.ijfoodmicro.2012.05.006. Epub 2012 May 14.
This study was designed to investigate the individual and combined effects of steam and lactic acid (LA) on the inactivation of biofilms formed by Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on polyvinyl chloride (PVC) and stainless steel. Six day old biofilms were developed on PVC and stainless steel coupons by using a mixture of three strains each of three foodborne pathogens at 25°C. After biofilm development, PVC and stainless steel coupons were treated with LA alone (immersed in 0.5% or 2% for 5s, 15s, and 30s), steam alone (on both sides for 5, 10, and 20s), and the combination of steam and LA. The numbers of biofilm cells of the three foodborne pathogens were significantly (p<0.05) reduced as the amount of LA and duration of steam exposure increased. There was a synergistic effect of steam and LA on the viability of biofilm cells of the three pathogens. For all biofilm cells of the three foodborne pathogens, reduction levels of individual treatments ranged from 0.11 to 2.12 log CFU/coupon. The combination treatment of steam and LA achieved an additional 0.2 to 2.11 log reduction compared to the sum of individual treatments. After a combined treatment of immersion in 2% LA for 15s or 30s followed by exposure to steam for 20s, biofilm cells of the three pathogens were reduced to below the detection limit (1.48 log). From the results of this study, bacterial populations of biofilms on PVC coupons did not receive the same thermal effect as on stainless steel coupons. Effectiveness of steam and LA may be attributed to the difference between Gram-negative and Gram-positive characteristics of the bacteria studied. The results of this study suggest that the combination of steam and LA has potential as a biofilm control intervention for food processing facilities.
本研究旨在探究蒸汽和乳酸(LA)单独及联合作用对 PVC 和不锈钢表面大肠埃希氏菌 O157:H7、鼠伤寒沙门氏菌和单增李斯特菌生物膜的灭活效果。采用三种食源性致病菌各三株混合液,于 25°C 条件下在 PVC 和不锈钢片上培养 6 天形成生物膜。生物膜形成后,将 PVC 和不锈钢片分别用 LA 单独处理(浸入 0.5%或 2%的 LA 溶液中 5s、15s 和 30s)、蒸汽单独处理(两侧各处理 5s、10s 和 20s),以及蒸汽和 LA 联合处理。随着 LA 用量和蒸汽暴露时间的增加,三种食源性致病菌的生物膜细胞数量均显著减少(p<0.05)。蒸汽和 LA 对三种致病菌生物膜细胞的存活具有协同作用。对于三种食源性致病菌的所有生物膜细胞,单独处理的减少水平范围为 0.11 至 2.12 对数 CFU/片。与单独处理的总和相比,蒸汽和 LA 的联合处理可额外减少 0.2 至 2.11 对数。经 15s 或 30s 浸入 2%LA 后,再用蒸汽处理 20s 的联合处理后,三种致病菌的生物膜细胞减少至检测限以下(1.48 对数)。本研究结果表明,PVC 片上生物膜的细菌群体没有像不锈钢片上那样受到相同的热效应。蒸汽和 LA 的有效性可能归因于所研究细菌的革兰氏阴性和阳性特征的差异。本研究结果表明,蒸汽和 LA 的联合使用具有作为食品加工设施生物膜控制干预的潜力。