Purpose: To investigate the use of an UVC LED (wavelength 250-280 nm, 20mW) to reduce Salmonella sp. on various surfaces.
Methods: Boneless skinless chicken breasts (CB) (2x2 cm), as well as flat stainless steel (SS) and teflon (TF) coupons (2x2 cm) were surface inoculated with a five-strain Salmonella cocktail at a target concentration of 6.5 Log10(CFU/cm2). Samples were treated with UVC LED light for up to 15 min. SS and CB (45 and 51 samples, respectively) were treated with varying average irradiance between 0–2 mW/cm2. A second study was conducted with CB and TF (54 samples each) using 0–4 mW/cm2 irradiance. After treatments, viable colonies were enumerated by plating onto XLT4 agar. D-values were calculated for each type of sample studied. A linear regression model was applied to predict the survival of bacterial cells, with a two-tailed t-test to estimate P-values for statistical differences between radiative doses.
Results: There was a significant reduction of Salmonella sp. due to the UV light exposure. D-values were statistically different from control samples (inoculated, not UVC LED treated). At 2 mW/cm2 irradiance, D-values for SS and CB were 0.64 min (CI 0.46-1.03) and 11.79 min (CI 8.15-21.31), respectively (P≤0.001). At 4 mW/cm2 irradiance, CB showed a D-value of 8.07 min (CI 5.84-13.04), and TF, 0.91 min (CI 0.82-1.02) (P≤0.001).
Significance: This preliminary research may allow development of a device for microbial control during food processing or food service environments.