Department of Food Technology, Safety and Health, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium; Center for Food Biotechnology and Microbiology, Ghent University Global Campus, Incheon 21985, Republic of Korea; Microbial Safety Team, National Institute of Agricultural Sciences, Rural Development Administration, Wanju 55365, Republic of Korea.
Microbial Safety Team, National Institute of Agricultural Sciences, Rural Development Administration, Wanju 55365, Republic of Korea.
Int J Food Microbiol. 2024 Aug 16;421:110800. doi: 10.1016/j.ijfoodmicro.2024.110800. Epub 2024 Jun 13.
To our knowledge, this study is the first to elucidate the bactericidal efficacy of unpeeled carrots (hereafter referred to as carrots) pretreated with Ultra Violet-C (UV-C) against subsequent contamination with Listeria monocytogenes. Carrots pretreated with UV-C (240 mJ/cm) exhibited a significant antilisterial effect within 2 h. In fact, the population of UV-C-pretreated carrots decreased from 7.94 log CFU/cm to levels below the limit of detection (LOD; <1.65 log CFU/cm) within 24 h. For carrots that were not pretreated with UV-C, 3-4 log reductions were found after 24 h. Carrots pretreated with UV-C exhibited antimicrobial activity against another gram-positive pathogen, Staphylococcus aureus, but not against the gram-negative pathogens, E. coli O157:H7 and Salmonella enterica. Pretreatment with UV-C created a lasting antimicrobial effect as introducing L. monocytogenes on carrots, 72 h post-UV-C treatment, still maintained the antilisterial effect. Notably, all UV-C doses in the range of 48-240 mJ/cm induced a lasting antilisterial effect. The bactericidal effects against L. monocytogenes were confirmed in three varieties of washed and unwashed carrots (Danvers, Nantes, and Chantenay). Fluorescence microscopy confirmed the bactericidal effect of UV-C-pretreated carrots on the survival of L. monocytogenes. Conclusively, pretreating carrots with UV-C can reduce the population of L. monocytogenes to levels below the LOD and may further prevent pathogen growth during cold storage. Additional studies are necessary to discern the mechanism underlying the bactericidal efficacy of UV-C-pretreated carrots.
据我们所知，这项研究首次阐明了未经去皮的胡萝卜（以下简称胡萝卜）经紫外线-C（UV-C）预处理后对李斯特菌随后污染的杀菌效果。经 UV-C（240 mJ/cm）预处理的胡萝卜在 2 小时内表现出显著的抗李斯特菌效果。事实上，UV-C 预处理的胡萝卜在 24 小时内从 7.94 log CFU/cm 降至检测限以下（<1.65 log CFU/cm）。对于未经 UV-C 预处理的胡萝卜，24 小时后发现减少了 3-4 个对数级。经 UV-C 预处理的胡萝卜对另一种革兰氏阳性病原体金黄色葡萄球菌表现出抗菌活性，但对革兰氏阴性病原体大肠杆菌 O157:H7 和肠炎沙门氏菌没有作用。UV-C 预处理会产生持久的抗菌效果，因为在 UV-C 处理后 72 小时将李斯特菌引入胡萝卜中，仍然保持抗李斯特菌的效果。值得注意的是，48-240 mJ/cm 范围内的所有 UV-C 剂量都诱导出持久的抗李斯特菌效果。在三种已清洗和未清洗的胡萝卜（丹弗斯、南特和坎特奈）中，荧光显微镜证实了 UV-C 预处理对李斯特菌存活的杀菌作用。总之，用 UV-C 预处理胡萝卜可以将李斯特菌的数量减少到检测限以下，并可能进一步防止冷藏期间病原体的生长。需要进一步的研究来确定 UV-C 预处理胡萝卜杀菌效果的机制。
