Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD, USA.
Food Quality Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD, USA.
Sci Rep. 2019 Aug 21;9(1):12170. doi: 10.1038/s41598-019-48597-0.
The 2014-2015 U.S. nationwide outbreak of listeriosis linked to apples used in commercially produced, prepackaged caramel apples was the first implication of whole apples in outbreaks of foodborne illnesses. Two case patients of this outbreak didn't consume caramel apples but did eat whole apples, suggesting that contaminated whole apple may serve as a vehicle for foodborne listeriosis. The current study evaluated the effect of conventional fruit coating with wax and that of apple cultivar on the survival of outbreak-associated and non-outbreak Listeria monocytogenes strains on Red Delicious, Granny Smith and Fuji apples during 160 days under simulated commercial storage. L. monocytogenes survived in calyxes and stem ends of apples of all 3 cultivars through the duration of the experiment. After 2 months of storage, significantly (p < 0.05) larger L. monocytogenes populations were recovered from apples coated with wax than those un-waxed, regardless of the cultivar. No differences in survival amongst L. monocytogenes strains (serotypes 1/2a and 4b) from clinical, food, and environmental sources were observed. The observation that coating with wax facilitates prolonged survival of L. monocytogenes on whole apples is novel and reveals gaps in understanding of microbiological risks associated with postharvest practices of tree fruit production.
2014-2015 年美国全国李斯特菌病暴发与用于商业生产的预包装焦糖苹果有关，这是首次发现整个苹果与食源性疾病暴发有关。暴发中的 2 例病例患者没有食用焦糖苹果，但食用了整个苹果，这表明受污染的整个苹果可能是食源性李斯特菌病的载体。本研究评估了常规水果涂蜡和苹果品种对在模拟商业储存条件下，160 天内红元帅、青苹果和富士苹果上与暴发相关和非暴发相关李斯特菌存活的影响。在整个实验过程中，在所有 3 个品种的苹果的果萼和果柄处李斯特菌都存活下来。储存 2 个月后，无论品种如何，涂蜡的苹果中李斯特菌的数量明显（p<0.05）多于未涂蜡的苹果。来自临床、食品和环境来源的 1/2a 和 4b 血清型李斯特菌的存活没有差异。涂蜡可延长整个苹果上李斯特菌存活时间的观察结果是新颖的，这揭示了对与水果生产的收获后实践相关的微生物风险的理解存在差距。
