Beyond antioxidant and antibacterial effects: Rosehip fruit extract as a powerful biofilm inhibitor against <i>S. aureus</i> and <i>L. monocytogenes</i> strains in dairy processing

Background, Context or Rationale Natural plant‐based antimicrobials are gaining attention in the dairy industry due to concerns over synthetic additives and antimicrobial resistance. Rosa canina (rosehip) is rich in bioactives, but its potential role in biofilm control remains underexplored. Aim This study aimed to evaluate the antioxidant, antimicrobial and antibiofilm potential of the rosehip fruit extract ( Rosa canina L., RC) obtained by using ethanol and microwave‐assisted extraction. Methods Antioxidant, antimicrobial and antibiofilm activities of the RC extract were investigated on strong biofilm‐forming Staphylococcus aureus (SAC9) and Listeria monocytogenes (LMP5 and LMC9) strains isolated from cheese samples. Antioxidant activity was assessed using the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging assay. Total phenolic and flavonoid contents were determined using standard spectrophotometric methods. Antimicrobial activity was determined using agar well diffusion, while the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were measured using a 96‐well microdilution assay. Biofilm formation and inhibition were determined using a crystal violet assay. Major Findings The RC extract exhibited significant antioxidant activity with SC 50 of 11.50 mg/mL by the DPPH assay. Total phenolic and total flavonoid contents were 8 mg GAE/g DW and 1.8 mg QE/g DW, respectively. The extract showed antimicrobial activity with the inhibition zone diameters between 6 and 14 mm, depending on the extract concentrations. MICs of the extract on SAC9, LMP5 and LMC9 strains were found to be 1.1, 2.2 and 2.2 mg/mL respectively. The extract exerted biofilm inhibitory activity (93–100%) across all strains. Minimal Biofilm Inhibitory Concentrations (MBICs) were determined as 4.4 mg/mL for SAC9, 0.2 mg/mL for LMP5 and 4.4 mg/mL for LMC9 strain biofilm formation. Scientific or Industrial implications RC extract demonstrated promising bioactive properties, antimicrobial and biofilm inhibitory effects, highlighting its potential as a natural alternative to synthetic antimicrobials in the dairy industry.