Institute of Sound and Vibration Research, University of Southampton, Southampton, UK.
Environmental Healthcare Unit, School of Biological Sciences, University of Southampton, Southampton, UK.
Ultrasound Med Biol. 2021 Jun;47(6):1616-1630. doi: 10.1016/j.ultrasmedbio.2021.01.026. Epub 2021 Feb 25.
In this study, we investigated the effects of an ultrasonically activated stream (UAS) on the removal of microbial contaminants from spinach leaves. The microbial loads on samples cleaned with and without UAS were enumerated using the cell culture method and compared against unwashed samples on day 0 and day 6 after cleaning. The effects of UAS cleaning on leaf quality were also examined through both macroscopic and microscopic inspection, as well as measurement of the electrolyte leakage rate. Results showed that the microbial load on samples cleaned with UAS for 2 min was significantly lower on day 6 after cleaning than on those treated without ultrasound. Comparison between the cleaning effects of UAS for 40 s versus 2 min indicated that a cleaning duration of 2 min allowed sufficient time for UAS to disaggregate and detach the microbial contamination more effectively. In this case, the induction of bacteria into a viable but non-culturable state does not affect the shelf-life test results as much as it does with a 40 s clean. UAS cleaning for 2 min did not produce significant surface damage, which can affect overall leaf quality. These findings highlight the potential of UAS systems in the salad industry to improve the microbiological quality and shelf life of salads.
在这项研究中，我们调查了超声激活流（UAS）对菠菜叶片上微生物污染物去除的影响。使用细胞培养法对使用和不使用 UAS 清洗的样品上的微生物负荷进行了计数，并与清洗前的未清洗样品在第 0 天和第 6 天进行了比较。还通过宏观和微观检查以及电解质泄漏率测量来检查 UAS 清洗对叶片质量的影响。结果表明，在清洗 2 分钟后，使用 UAS 清洗的样品上的微生物负荷在清洗 6 天后明显低于未超声处理的样品。UAS 清洗 40 秒与 2 分钟的清洗效果比较表明，清洗 2 分钟的时间足以使 UAS 更有效地分散和去除微生物污染。在这种情况下，细菌进入可培养但不可培养状态的诱导不会像清洗 40 秒那样对保质期测试结果产生太大影响。UAS 清洗 2 分钟不会产生明显的表面损伤，这会影响整体叶片质量。这些发现突出了 UAS 系统在沙拉行业中的潜力，可提高沙拉的微生物质量和保质期。
