Preparation of Zn@ChNFs and Their Effects on Pathogen-Contaminated Microgreen Growth via Antimicrobial Activity and Oxidative Enzyme Modulation

Microgreen production is highly vulnerable to seed-borne contamination by foodborne pathogens, compromising food safety and plant performance. In this study, zinc-modified chitin nanofibers (Zn@ChNFs) were prepared and characterized as a multifunctional nanomaterial to simultaneously control microbial contamination and enhance microgreen growth. Zn@ChNFs were synthesized via ammonium persulfate oxidation followed by Zn coordination, maintaining the native nanofibrous structure of ChNFs while achieving a maximum Zn loading of 2.9%. The Zn@ChNFs exhibited substantially enhanced antimicrobial activity against Listeria monocytogenes, resulting in more than 1.04 log CFU/g reduction on contaminated radish seeds and sustained pathogen suppression during microgreen growth. Compared with water and pure ChNFs treatments, Zn@ChNFs significantly improved seed germination, shoot length, leaf area, and biomass accumulation under bacterial stress. Furthermore, Zn@ChNFs promoted nitrogen assimilation and chlorophyll biosynthesis, thereby improving photosynthetic performance. Nutritional and biochemical analyses revealed increased protein, polyphenol, and flavonoid contents, accompanied by enhanced DPPH and ABTS antioxidant capacities. The activities of key antioxidant enzymes, catalase and peroxidase, were also markedly elevated, indicating effective mitigation of pathogen-induced oxidative stress. Collectively, these results demonstrate that Zn@ChNFs offer an integrated antimicrobial and nutritional approach, providing a sustainable nanomaterial platform for improving both microbial safety and nutritional quality in microgreen production.