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 Escherichia coli and Staphylococcus aureus (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 Escherichia coli and Staphylococcus aureus), 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.