Effect of cinnamaldehyde pickering emulsion on Pseudomonas fragi biofilms: Characterization, antibiofilm effects in vitro and in vivo, and a transcriptomic analysis

<i>Pseudomonas fragi (P. fragi)</i>, a predominant biofilm-forming spoilage bacterium in fresh chilled meat, causes persistent contamination and poses a significant food safety concern. However, research on its biofilms remains exploratory, and effective control measures are currently lacking. This study developed an innovative biofilm-targeted preservation system by encapsulating cinnamaldehyde (CA), the most potent essential oil component against <i>P. fragi</i> (MIC = 0.3125 mg/mL), within a Pickering emulsion to overcome its inherent volatility and poor aqueous solubility. Molecular docking simulations revealed stable interactions among whey protein isolate (WPI), sunflower oil, and CA, guiding rational emulsion design. The optimized emulsion (oil-water ratio 6:4) exhibited excellent physical stability (particle size: 11.30 ± 1.88 μm; zeta potential: -31.6 ± 0.82 mV), oxidation stability, and sustained-release properties, along with biosafety validated by murine acute toxicity and hemolysis assays. Crucially, while maintaining identical MIC values to free CA, the CA Pickering emulsion demonstrated significantly enhanced biofilm inhibition and eradication capabilities against <i>P. fragi.</i> Transcriptomic analysis revealed, for the first time, that the CA emulsion induced dysregulation of 191 bacterial genes (114 downregulated, 77 upregulated), which simultaneously suppressed signaling and metabolic pathways while inducing stress adaptation responses, thereby disrupting biofilm formation and maintenance. This work establishes a novel stabilization paradigm for essential oils and provides a theoretical foundation for developing green biofilm-targeting technologies against meat spoilage bacteria, facilitating the practical applications of CA Pickering emulsions in meat preservation.