Photodynamic inactivation of curcumin combined with ascorbic acid against Penicillium italicum in vitro and on fresh-cut orange

This study investigated the antifungal effect of curcumin-mediated photodynamic inactivation (PDI) with ascorbic acid (Vc) as a synergist on Penicillium italicum and its biofilms, and evaluated the efficacy in inactivating P. italicum on fresh-cut orange. Results showed that the number of P. italicum spores decreased by 4.61 Log CFU/mL when the concentration of curcumin, Vc and illumination time was 75 μmol/L, 250 mg/L and 20 min, respectively. After PDI treatment, the cell structure of P. italicum was destroyed and leakage of cell contents was observed. Mature P. italicum biofilms were formed after 72 h of incubation, and PDI could reduce the spores in biofilms by 3.23 Log CFU/mL. In addition, under the optimal photodynamic conditions, the number of P. italicum spores in fresh-cut orange decreased by 2.48 Log CFU/g, and the sensory quality was well maintained. In conclusion, curcumin-mediated photodynamic technology could better maintain the freshness of fresh-cut orange. Therefore, this study deepened the understanding of the antimicrobial efficacy of curcumin-mediated PDI on food borne pathogens and its impact on food quality.