Assessment of antimicrobial properties of a curcumin-loaded nano-emulsion in reducing pathogen loads on cantaloupe surface (Cucumis melo L.)

Abstract

Curcumin (CUR) exhibits antimicrobial properties but is hindered by chemical instability, limiting its direct application. This study evaluated the efficacy of curcumin nanoemulsions (CUR-NE) in reducing pathogenic microorganisms on cantaloupe rind surfaces. Two CUR-NE formulations, 1CUR-NE (0.05% CUR, w/w) and 2CUR-NE (0.10% CUR, w/w), were prepared by mixing CUR with medium-chain triglyceride (MCT) oil (3% w/w), polysorbate 80 (2% w/w), and polyethylene glycol (10% w/w), followed by a 15-min ultrasound treatment (175 W). The antimicrobial effects were assessed against Listeria innocua B-33016, Escherichia coli ATCC25922, aerobic bacteria, and yeast and mold. Inoculated cantaloupe surfaces were treated with CUR-NE, and microbial counts were analyzed on days 1, 3, 6, 9, and 12. The viscosity of 1CUR-NE and 2CUR-NE was 0.0030 ± 0.0001 Pa s and 0.0027 ± 0.0006 Pa s, with droplet sizes of 122.47 ± 3.06 nm and 137.67 ± 1.36 nm, respectively. Treatment with 2CUR-NE significantly reduced L. innocua growth on day 6 (2.50 ± 1.00 log CFU/cm²), with E. coli showing significant reductions on days 6 (1.55 ± 0.40 log CFU/cm²), 9 (1.91 ± 0.36 log CFU/cm²), and 12 (0.72 ± 0.26 log CFU/cm²). Scanning electron microscopy revealed a substantial decrease in microbial load after treatment. The results suggest that CUR-NE, particularly 2CUR-NE, effectively reduces pathogenic contamination on cantaloupe and offers a potential alternative to synthetic antimicrobial agents in food safety applications. Further studies are needed to explore the long-term efficacy and broader applications of CUR-NE in food systems.