Antibacterial activity of angelica essential oil, its mechanism against Pseudomonas fluorescens, and its application in the preservation of chilled fresh beef

The mechanism by which Angelica essential oil (AEO) can act as an antimicrobial agent at cellular and metabolic levels to inhibit Pseudomonas fluorescens (P. fluorescens), and its effectiveness in beef preservation, were investigated and evaluated in this study. Our results showed that the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of AEO to P. fluorescens were 12.5 μL/mL and 25 μL/mL, respectively, at which AEO could effectively inhibit P. fluorescens reproduction and retard its growth (p < 0.05). Severe morphological damage to the AEO-treated cells of the microorganism, including cell walls and membranes, were observed via scanning electron microscopy (SEM). AEO treatment was also seen to lead to an increase in alkaline phosphatase (AKPase) activity and conductivity, and a significant leakage of intracellular macromolecular components (such as nucleic acids and proteins), providing further evidence of damage to the integrity of cell wall and cell membrane. Metabolomics analysis revealed that the differential metabolites in the AEO hindered nucleic acid synthesis and expression in the P. fluorescens, leading to tricarboxylic acid (TCA) cycle blockage and amino acid restriction, energy metabolism disorders and membrane damage, mainly through nucleotide metabolism, amino acid metabolism, carbohydrate metabolism and membrane transport. Moreover, application testing demonstrated the efficacy of AEO in slowing the increase of beef pH and total volatile basic nitrogen (TVB-N), extending the shelf life of chilled beef by 5.39 d, and effectively maintaining the organoleptic quality of beef. These results lay a foundation for the development of AEO as a natural bacteriostatic agent.