Study of the Factors Involved in the Adhesion Process of Salmonella enterica Enteritidis, Escherichia coli, and Staphylococcus aureus to the Surface of Apple, Arugula, Cucumber, and Strawberry

Bacterial contamination of fresh produce remains a global food safety concern, with pathogens such as <i>Salmonella</i>, <i>Escherichia coli</i>, and <i>Staphylococcus aureus</i> frequently implicated in foodborne outbreaks. Understanding the physicochemical factors involved in bacterial adhesion to fresh produce surfaces is essential for developing effective sanitization strategies. This study evaluated the influence of surface roughness, hydrophobicity, thermodynamic free energy, and temperature on pathogen adhesion to apple, arugula, cucumber, and strawberry. Surface roughness varied significantly among produce types (2.51-5.86 µm), with arugula exhibiting the highest values. Hydrophobicity assessments revealed discrepancies between qualitative (contact angle-based) and quantitative (free energy-based) methods: while all produce were classified as hydrophobic qualitatively, strawberry was hydrophilic by quantitative analysis. All bacterial species tested were hydrophilic qualitatively, but <i>E. coli</i> showed hydrophobic character quantitatively. Thermodynamic predictions of adhesion (Δ<i>G_adhesion</i>) did not predict observed adhesion bacterial counts (5.07-6.20 log CFU·g^-1), with substantial bacterial attachment occurring even when thermodynamically unfavorable (positive Δ<i>G_adhesion</i>), indicating that biological factors override physicochemical interactions. Temperature deeply influenced adhesion, with 25 °C promoting 0.3-3.5 log CFU·g^-1-higher bacterial counts than 7 °C across all combinations (<i>p</i>-value ≤ 0.05). These findings demonstrate that bacterial adhesion to fresh produce is multifactorial, with temperature as the dominant controllable factor, and highlight the need for integrated sanitation approaches combining physical and chemical treatments applied before refrigerated storage.