Rao Aishwarya Pradeep, Pradhan Abani K, Patel Jitendra
Department of Nutrition and Food Science, University of Maryland, College Park, Maryland, USA; US Department of Agriculture, Agricultural Research Service, Environmental, Microbial and Food Safety Laboratory, Beltsville, Maryland, USA.
Department of Nutrition and Food Science, University of Maryland, College Park, Maryland, USA; Center for Food Safety and Security Systems, University of Maryland, College Park, Maryland, USA.
J Food Prot. 2025 Aug 5;88(10):100594. doi: 10.1016/j.jfp.2025.100594.
Microgreens, like leafy greens, are susceptible to contamination at the preharvest stage, posing food safety concerns, particularly as their consumption rises due to their recognized bioactive benefits. Recalls associated with microgreens have further underscored these concerns. This study aimed to investigate the potential transfer of enteric pathogens to microgreens irrigated with contaminated water. Municipal water (MW) and rainwater (RW) inoculated with low and high concentrations of Salmonella enterica, Escherichia coli O157:H7, or Listeria monocytogenes were used to irrigate daikon, red cabbage, broccoli, and mustard microgreens cultivated on soil beds. Microgreen and soil samples were collected on days 7 and 14 and analyzed using most probable number (MPN) enumeration or spiral plating on selective media. Significant variations in pathogen recovery were observed across days 7 and 14, irrespective of microgreen variety or water source. When irrigated with water at 5 Log CFU/mL contamination level, all pathogens were significantly reduced by ∼2.5-4.7 Log CFU/g on 14th day, irrespective of microgreens or source of irrigation water. A similar trend was observed with pathogens at low inoculation (3 Log CFU/mL); however, the reduction on day 14 was not significant (1.9-3 Log MPN/g) except for broccoli and daikon microgreens inoculated with Salmonella. At low and high levels of inoculums, L. monocytogenes persisted in lower numbers (2-2.5 Log MPN/g and 3.9-4.1 Log CFU/g) on microgreens compared to Salmonella (3.2-3.8 Log MPN/g and 4.2-4.5 Log CFU/g) and E. coli O157:H7 (2.8-3.4 Log MPN/g and 4.5-4.7 Log CFU/g), respectively, throughout the sampling period. The source of irrigation water affected the persistence of pathogens; Salmonella and E. coli O157:H7 persisted in lower numbers (2.2-2.7 and 2.1-2.5 Log MPN/g, respectively) for low inoculum on microgreens irrigated with RW. Recovery of L. monocytogenes from microgreens irrigated with MW at low inoculum was significantly lower compared to that of E. coli O157:H7 at 7 days. These findings highlight the potential for transfer of enteric pathogens from contaminated irrigation water to the edible portions of microgreens, emphasizing the importance of rigorous microbial quality control of irrigation water in controlled environmental agriculture (CEA) to mitigate contamination risks.
微型蔬菜与绿叶蔬菜一样，在收获前阶段容易受到污染，引发食品安全问题，尤其是随着其因公认的生物活性益处而消费量上升。与微型蔬菜相关的召回事件进一步凸显了这些担忧。本研究旨在调查肠道病原体向用受污染水灌溉的微型蔬菜的潜在转移情况。用接种了低浓度和高浓度肠炎沙门氏菌、大肠杆菌O157:H7或单核细胞增生李斯特菌的市政用水（MW）和雨水（RW）来灌溉种植在土壤苗床上的萝卜、红甘蓝、西兰花和芥菜微型蔬菜。在第7天和第14天采集微型蔬菜和土壤样本，并使用最可能数（MPN）计数法或在选择性培养基上进行螺旋平板接种法进行分析。无论微型蔬菜品种或水源如何，在第7天和第14天观察到病原体回收率存在显著差异。当用污染水平为5 Log CFU/mL的水灌溉时，在第14天，所有病原体均显著减少了约2.5 - 4.7 Log CFU/g，无论微型蔬菜种类或灌溉水源如何。对于低接种量（3 Log CFU/mL）的病原体也观察到类似趋势；然而，除了接种沙门氏菌的西兰花和萝卜微型蔬菜外，第14天的减少量不显著（1.9 - 3 Log MPN/g）。在低接种量和高接种量水平下，与沙门氏菌（3.2 - 3.8 Log MPN/g和4.2 - 4.5 Log CFU/g）和大肠杆菌O157:H7（2.8 - 3.4 Log MPN/g和4.5 - 4.7 Log CFU/g）相比，单核细胞增生李斯特菌在微型蔬菜上的存活数量较少（2 - 2.5 Log MPN/g和3.9 - 4.1 Log CFU/g），在整个采样期间均如此。灌溉水源影响病原体的存活；对于低接种量，用雨水灌溉的微型蔬菜上，沙门氏菌和大肠杆菌O157:H7的存活数量较少（分别为2.2 - 2.7和2.1 - 2.5 Log MPN/g）。在低接种量时，与大肠杆菌O157:H7相比，从用市政用水灌溉的微型蔬菜中回收的单核细胞增生李斯特菌在第7天显著更低。这些发现凸显了肠道病原体从受污染的灌溉水转移到微型蔬菜可食用部分的可能性，强调了在可控环境农业（CEA）中对灌溉水进行严格微生物质量控制以降低污染风险的重要性。
