Department of Food Science and Human Nutrition, Michigan State University, East Lansing, Michigan 48824, USA; Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA.
Department of Food Science and Human Nutrition, Michigan State University, East Lansing, Michigan 48824, USA; Department of Food Science and Technology, University of California, Davis, Davis, CA 95616, USA.
J Food Prot. 2014 May;77(5):765-71. doi: 10.4315/0362-028X.JFP-13-382.
The transfer of Listeria monocytogenes to previously uncontaminated product during mechanical dicing of celery and its growth during storage at various temperatures were evaluated. In each of three trials, 275 g of retail celery stalks was immersed in an aqueous five-strain L. monocytogenes cocktail to obtain an average of 5.6 log CFU/g and then was diced using a hand-operated dicer, followed by sequential dicing of 15 identical 250-g batches of uninoculated celery using the same dicer. Each batch of diced celery was examined for numbers of Listeria initially and after 3 and 7 days of storage at 4, 7, and 10 °C. Additionally, the percentage by weight of inoculated product transferred to each of 15 batches of uninoculated celery was determined using inoculated red stems of Swiss chard as a surrogate. Listeria transfer to diced celery was also assessed after removing the Swiss chard. L. monocytogenes transferred from the initial batch of inoculated celery to all 15 batches of uninoculated celery during dicing, with populations decreasing from 5.2 to 2.0 log CFU/g on the day of processing. At 10 °C, Listeria reached an average population of 3.4 log CFU/g in all batches of uninoculated celery. Fewer batches of celery showed significant growth during storage at 4 and 7 °C (P < 0.05). Swiss chard pieces were recovered from all 15 batches of celery, with similar amounts seen in batches 2 to 15 (P > 0.05). L. monocytogenes was also recovered from each batch of uninoculated celery after the removal of Swiss chard, with populations decreasing from 4.7 to 1.7 log CFU/g. Storing the diced celery at 10 °C yielded a L. monocytogenes generation time of 0.87 days, with no significant growth observed during storage at 4 or 7 °C. Consequently, mitigation strategies during dicing and proper refrigeration are essential to minimizing potential health risks associated with diced celery.
研究了单核细胞增生李斯特菌（Listeria monocytogenes）在机械切割芹菜过程中转移到先前未受污染的产品中以及在不同温度下储存期间的生长情况。在三次试验中的每一次，将 275 克零售芹菜茎浸入含五株李斯特菌的水性鸡尾酒中，获得平均 5.6logCFU/g 的菌液，然后使用手动切菜机进行切割，随后使用同一切菜机连续切割 15 个相同的 250 克未接种芹菜批次。每批切割的芹菜在 4、7 和 10°C 下储存 3 和 7 天后，最初和之后都检测李斯特菌数量。此外，使用瑞士甜菜的接种红茎作为替代物，确定接种产品转移到 15 批未接种芹菜中的重量百分比。在去除瑞士甜菜后，还评估了李斯特菌向切丁芹菜的转移情况。在切割过程中，初始接种芹菜批次中的李斯特菌转移到所有 15 批未接种的芹菜批次中，接种后第 1 天，细菌数量从 5.2 减少到 2.0logCFU/g。在 10°C 下，所有未接种芹菜批次中的李斯特菌平均达到 3.4logCFU/g。在 4 和 7°C 下储存时，较少批次的芹菜显示出显著的生长（P<0.05）。在所有 15 批芹菜中都回收了瑞士甜菜块，第 2 到 15 批中观察到的量相似（P>0.05）。在去除瑞士甜菜后，也从每批未接种的芹菜中回收了李斯特菌，细菌数量从 4.7 减少到 1.7logCFU/g。将切丁的芹菜储存在 10°C 下，李斯特菌的世代时间为 0.87 天，在 4 或 7°C 下储存时没有观察到明显的生长。因此，在切割过程中采取缓解策略和适当的冷藏对于最大限度地降低与切丁芹菜相关的潜在健康风险至关重要。
