Effects of Violet-Blue Light-Emitting Diode on Controlling Bacterial Contamination in Boiled Young Sardine.

The aim of this study was to evaluate bacterial decontamination of boiled young sardine by treatment with violet-blue light followed by cooling storage of the irradiated boiled sardine. Viable cell count in the samples was evaluated after irradiation with four types of violet-blue light-emitting diodes (LEDs; peak wavelength at 405, 412, 421 or 455 nm) and subsequent cooling storage for two days. LED (405 nm) exhibited bactericidal and growth suppression effects. The irradiation gave a 47% bactericidal rate in comparison with no irradiation samples (control) and the two-day storage suppressed the increase in cell counts to 24%, while the rate of increase was 545% for the control. Integrated viability (IV) based on growth delay analysis was estimated after irradiation of four isolates from boiled sardine with 405 nm light. The irradiation caused growth delay against all isolates, resulting in smaller IV values for three isolates compared to those viabilities estimated from colony forming units. Exposure (405 nm) at 432 J/cm fluence resulted in a decrease in water content, resulting in an increase in salinity of the samples. This study demonstrated the advantages of light emitting a narrow violet region as a non-thermal disinfection technology in the processing and storage of boiled sardines.