Refrigeration temperature enhanced synergistic interaction of curcumin and 460 nm light-emitting diode against Staphylococcus saprophyticus at neutral pH

Abstract Objectives As considered highly resistant to antibiotics like mecillinam, the rise of Staphylococcus saprophyticus (S. saprophyticus) contamination of fresh foods and food processing environments necessitates the development of a new antimicrobial approach for food safety control. This study aimed to investigate the synergistic effect of food-grade curcumin (CUR) and blue light-emitting diode (LED) on S. saprophyticus. Materials and Methods S. saprophyticus was subjected to the synergistic treatment at 4 and 25 °C. The influence of parameters, including CUR concentration, light dose, and pH incubation time on the inactivation of S. saprophyticus was characterized through plate counting method. Results: The combined treatment of CUR and blue light irradiation significantly (P < 0.05) reduced bacterial counts and the antimicrobial effect was in a CUR concentration and light dose-dependent manner. Moreover, refrigeration temperature (4 °C) significantly (P < 0.05) enhanced the antibacterial effect at neutral pH condition (6.2–7.2), resulting in approximately 6.0 log reductions. Under acidic condition (pH 2.2–5.2), there was no significant difference in bacterial population reduction between treatments at both temperatures. Conclusions These findings proposed that synergistic interaction of CUR and 460 nm LED under refrigerated temperature could enhance the inactivation of S. saprophyticus at neutral pH condition.