Abstract:
Bacteria including Vibrio spp. persist in coastal waters and can contaminate edible seaweeds. Pathogens such as Listeria monocytogenes, shigatoxigenic Escherichia coli (STEC), and Salmonella have been associated with and present serious health risks in minimally processed vegetables including seaweeds. This study evaluated the survival of four pathogens inoculated onto two product forms of sugar kelp subjected to different storage temperatures. The inoculation comprised of a cocktail of two Listeria monocytogenes and STEC strains, two Salmonella serovars, and two Vibrio species. STEC and Vibrio were grown and applied in salt-containing media to simulate preharvest contamination, whereas L. monocytogenes and Salmonella inocula were prepared to simulate postharvest contamination. Samples were stored at 4°C and 10°C for 7 days, and 22°C for 8 h. Microbiological analyses were performed periodically (1, 4, 8, 24 h, etc.) to evaluate the effects of storage temperature on pathogen survival. Pathogen populations decreased under all storage conditions, but survival was greatest for all species at 22°C, with STEC exhibiting significantly less reduction (1.8 log CFU/g) than Salmonella, L. monocytogenes, and Vibrio (3.1, 2.7, and 2.7 log CFU/g, respectively) after storage. The largest population reduction (5.3 log CFU/g) was observed in Vibrio stored at 4°C for 7 days. Regardless of storage temperature, all pathogens remained detectable at the end of the study duration. Results emphasize the need for strict adherence to temperature control for kelp as temperature abuse may support pathogen survival, especially STEC, during storage, and the need for prevention of postharvest contamination, particularly with Salmonella.
摘要:
包括弧菌的细菌。持续存在于沿海水域,并可能污染可食用的海藻。病原体如单核细胞增生李斯特菌,产志贺毒素大肠杆菌(STEC)和沙门氏菌与包括海藻在内的最低加工蔬菜有关,并存在严重的健康风险。这项研究评估了接种到两种产品形式的糖海带上的四种病原体在不同储存温度下的存活率。接种由两种单核细胞增生李斯特菌和STEC菌株组成的混合物,两种沙门氏菌血清型和两种弧菌。STEC和弧菌生长并应用于含盐培养基中以模拟收获前的污染,而单核细胞增生李斯特菌和沙门氏菌接种物被制备来模拟收获后的污染。将样品在4°C和10°C下储存7天,和22°C持续8小时。定期进行微生物分析(1、4、8、24小时,等。)评价贮藏温度对病原菌存活的影响。在所有储存条件下病原体种群减少,但是所有物种在22°C时的存活率最高,与沙门氏菌相比,STEC的减少量(1.8logCFU/g)显着减少,单核细胞增生利氏菌和弧菌(3.1、2.7和2.7logCFU/g,分别)储存后。在4°C下储存7天的弧菌中观察到最大的群体减少(5.3logCFU/g)。无论储存温度如何,在研究期间结束时,所有病原体仍可检测到.结果强调必须严格遵守海带的温度控制,因为温度滥用可能会支持病原体的生存。尤其是STEC,储存期间,以及预防采后污染的需要,特别是沙门氏菌。