Dykes G A, Vegar M, Vanderlinde P B
Food Science Australia, Tingalpa DC, Queensland, Australia.
Lett Appl Microbiol. 2003;37(4):309-13. doi: 10.1046/j.1472-765x.2003.01395.x.
To quantify Listeria levels on the shell and flesh of artificially contaminated cooked prawns after peeling, and determine the efficacy of Listeria innocua as a model for L. monocytogenes in this system.
A L. monocytogenes and L. innocua strain were inoculated separately onto cooked black tiger prawns using two protocols (immersion or swabbing with incubation). Prawns were peeled by two methods (gloved hand or scalpel and forceps) and numbers of Listeria on shells, flesh and whole prawn controls were determined. Prawns were exposed to crystal violet dye to assess the penetration of liquids. Regardless of preparation method or bacterial strain there were ca 1log10 CFU more Listeria per shell than per peeled prawn. Dye was able to penetrate to the flesh in all cases.
Shell-on prawns may be only slightly safer than shell-off prawns. Listeria innocua is an acceptable model for L. monocytogenes in this system.
Reduced risk from L. monocytogenes on prawns can only be assured by adequate hygiene or heating.
量化人工污染的熟虾去壳后虾壳和虾肉上的李斯特菌水平，并确定无害李斯特菌作为该系统中单核细胞增生李斯特菌模型的有效性。
使用两种方案（浸泡或涂抹并培养）将单核细胞增生李斯特菌和无害李斯特菌菌株分别接种到熟黑虎虾上。通过两种方法（戴手套的手或手术刀和镊子）对虾进行去壳，并测定虾壳、虾肉和整个虾对照上的李斯特菌数量。将虾暴露于结晶紫染料中以评估液体的渗透情况。无论制备方法或细菌菌株如何，每只虾壳上的李斯特菌数量比每只去壳虾多约1个对数CFU。在所有情况下，染料都能渗透到虾肉中。
带壳虾可能仅比去壳虾略安全。无害李斯特菌是该系统中单核细胞增生李斯特菌的可接受模型。
只有通过适当的卫生措施或加热才能确保虾上单核细胞增生李斯特菌带来的风险降低。
