Tannic Acid-Modified Sodium Caseinate Pickering Emulsion Coatings: Characterization, Enhanced Mechanical/Antibacterial Properties, and Application in Cherry Tomato Preservation

This study developed a tannic acid-modified sodium caseinate (SC-TA) stabilized Pickering emulsion containing bergamot essential oil (BEO) and carboxymethyl tara gum for cherry tomato preservation. Fourier transform infrared (FTIR) spectroscopy and circular dichroism (CD) analysis confirmed successful SC-TA conjugation and improved emulsion stability. The emulsion significantly lowered the water vapor permeability (WVP) of the film, enhanced its tensile strength and elongation, and exhibited antimicrobial activity against <i>Escherichia coli</i> and <i>Staphylococcus aureus</i> (the inhibition zones of the coating with Pickering emulsion were 10.67 mm larger and 6.67 mm larger than those without Pickering emulsion, respectively, against <i>Escherichia coli</i> and <i>Staphylococcus aureus</i>), as well as antioxidant capabilities (the coating with Pickering emulsion showed a 128.6% increase in DPPH scavenging rate and a 341.8% increase in ABTS scavenging rate compared to the coating without Pickering emulsion). Applied to cherry tomatoes, it effectively reduced quality deterioration by minimizing weight/firmness loss, preserving nutrients (vitamin C, lycopene), and decreasing oxidative damage. These comprehensive effects confirm that the BEO-stabilized Pickering emulsion coating represents a promising technology for postharvest management, capable of extending fruit shelf life while preserving nutritional quality.