Niemira Brendan A, Boyd Glenn, Sites Joseph
Food Safety and Intervention Technologies Research Unit, Eastern Regional Research Center, U.S. Dept. of Agriculture, Agricultural Research Service, Wyndmoor, PA 19038, U.S.A.
J Food Sci. 2014 May;79(5):M917-22. doi: 10.1111/1750-3841.12379. Epub 2014 Apr 17.
Cross-contamination of foods from persistent pathogen reservoirs is a known risk factor in processing environments. Industry requires a rapid, waterless, zero-contact, chemical-free method for removing pathogens from food contact surfaces. Cold plasma was tested for its ability to inactivate Salmonella biofilms. A 3-strain Salmonella culture was grown to form adherent biofilms for 24, 48, or 72 h on a test surface (glass slides). These were placed on a conveyor belt and passed at various line speeds to provide exposure times of 5, 10, or 15 s. The test plate was either 5 or 7.5 cm under a plasma jet emitter operating at 1 atm using filtered air as the feed gas. The frequency of high-voltage electricity was varied from 23 to 48 kHz. At the closer spacing (5 cm), cold plasma reduced Salmonella biofilms by up to 1.57 log CFU/mL (5 s), 1.82 log CFU/mL (10 s), and 2.13 log CFU/mL (15 s). Increasing the distance to 7.5 cm generally reduced the efficacy of the 15 s treatment, but had variable effects on the 5 and 10 s treatments. Variation of the high-voltage electricity had a greater effect on 10 and 15 s treatments, particularly at the 7.5 cm spacing. For each combination of time, distance, and frequency, Salmonella biofilms of 24, 48, and 72 h growth responded consistently with each other. The results show that short treatments with cold plasma yielded up to a 2.13 log reduction of a durable form of Salmonella contamination on a model food contact surface. This technology shows promise as a possible tool for rapid disinfection of materials associated with food processing.
Pathogens such as Salmonella can form chemical-resistant biofilms, making them difficult to remove from food contact surfaces. A 15 s treatment with cold plasma reduced mature Salmonella biofilms by up to 2.13 log CFU/mL (99.3%). This contact-free, waterless method uses no chemical sanitizers. Cold plasma may therefore have a practical application for conveyor belts, equipment, and other food contact surfaces where a rapid, dry antimicrobial process is required.
来自持久性病原体储存库的食品交叉污染是加工环境中已知的风险因素。食品行业需要一种快速、无水、零接触、无化学物质的方法来去除食品接触表面的病原体。对冷等离子体灭活沙门氏菌生物膜的能力进行了测试。将一种三菌株沙门氏菌培养物在测试表面（载玻片）上培养24、48或72小时以形成附着的生物膜。将这些载玻片放置在传送带上，并以不同的线速度通过，以提供5、10或15秒的暴露时间。测试板位于以1个大气压运行的等离子体射流发射器下方5或7.5厘米处，使用过滤空气作为进料气体。高压电的频率在23至48千赫兹之间变化。在较近的间距（5厘米）下，冷等离子体使沙门氏菌生物膜减少多达1.57 log CFU/mL（5秒）、1.82 log CFU/mL（10秒）和2.13 log CFU/mL（15秒）。将距离增加到7.5厘米通常会降低15秒处理的效果，但对5秒和10秒处理的影响各不相同。高压电的变化对10秒和15秒处理的影响更大，尤其是在7.5厘米的间距下。对于时间、距离和频率的每种组合，生长24、48和72小时的沙门氏菌生物膜之间的反应一致。结果表明，用冷等离子体进行短时间处理可使模拟食品接触表面上持久形式的沙门氏菌污染减少多达2.13 log。这项技术有望成为对与食品加工相关的材料进行快速消毒的一种可能工具。
沙门氏菌等病原体会形成耐化学物质的生物膜，使其难以从食品接触表面去除。用冷等离子体处理15秒可使成熟的沙门氏菌生物膜减少多达2.13 log CFU/mL（99.3%）。这种无接触、无水的方法不使用化学消毒剂。因此，冷等离子体可能在需要快速、干式抗菌过程的传送带、设备和其他食品接触表面上有实际应用。
