Abstract The aim of the present study was to investigate Listeria innocua (used as a surrogate for Listeria monocytogenes) dynamics in a laboratory-scale food chain of mealworm (Tenebrio molitor) larvae. To this end, a rearing substrate consisting of organic wheat middlings was spiked with L. innocua cells at three different contamination levels, namely 1, 5 and 7 Log colony-forming units (cfu) per gram. The dynamics of L. innocua were evaluated in larvae and frass samples collected during a 7-day rearing period. The effect of washing on the L. innocua load in the larvae at the end of the rearing period was assessed. Subsequently, the ability of four food treatment technologies (boiling, oven cooking, deep-frying, and freeze-drying) to kill L. innocua cells in the unwashed larvae was also evaluated. The overall results suggested that once L. innocua becomes established in the rearing environment, even at low levels, it may multiply in both the rearing substrate and the gut of larvae, representing a threat for the health of consumers. Regarding the processing of larvae, washing had no effect on the load of the test microorganism, whereas, as expected, the three heat-based food treatments (boiling, oven cooking, and deep frying) effectively killed all the Listeria cells carried by the larvae. Finally, frass generated by insects during rearing proved to be a potential source of environmental and food Listeria spp. contamination when not properly managed and disposed.

中文翻译：

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供人类食用的黄粉虫幼虫（黄粉虫）实验室规模食物链中的李斯特菌动态

摘要 本研究的目的是在实验室规模的粉虫（黄粉虫）幼虫食物链中研究无害李斯特菌（用作单核细胞增生李斯特菌的替代品）动态。为此，在三个不同污染水平，即每克 1、5 和 7 Log 菌落形成单位 (cfu) 的情况下，在由有机小麦中胚层组成的饲养基质中加入无害李斯特菌细胞。L. innocua 的动态在 7 天饲养期间收集的幼虫和碎屑样品中进行了评估。评估了在饲养期结束时清洗对幼虫中无害李斯特菌负荷的影响。随后，还评估了四种食品处理技术（煮沸、烤箱烹饪、油炸和冷冻干燥）杀死未洗涤幼虫中无害李斯特菌细胞的能力。总体结果表明，一旦 L. innocua 在饲养环境中建立，即使水平很低，它也可能在饲养基质和幼虫肠道中繁殖，对消费者的健康构成威胁。关于幼虫的处理，洗涤对测试微生物的负荷没有影响，而正如预期的那样，三种基于加热的食物处理（煮沸、烤箱烹饪和油炸）有效地杀死了幼虫携带的所有李斯特菌细胞. 最后，昆虫在饲养过程中产生的粪便被证明是环境和食品李斯特菌的潜在来源。如果管理和处置不当，就会受到污染。洗涤对测试微生物的负荷没有影响，而正如预期的那样，三种基于热的食物处理（煮沸、烤箱烹饪和油炸）有效地杀死了幼虫携带的所有李斯特菌细胞。最后，昆虫在饲养过程中产生的粪便被证明是环境和食品李斯特菌的潜在来源。如果管理和处置不当，就会受到污染。洗涤对测试微生物的负荷没有影响，而正如预期的那样，三种基于热的食物处理（煮沸、烤箱烹饪和油炸）有效地杀死了幼虫携带的所有李斯特菌细胞。最后，昆虫在饲养过程中产生的粪便被证明是环境和食品李斯特菌的潜在来源。如果管理和处置不当，就会受到污染。