Use of LED Ultraviolet (UV) Light for the Reduction of Salmonella sp. on Surface of Chicken and Food Contact Surfaces

Introduction: The use of ultraviolet light has been proven to be effective for microbial inactivation.  Ultraviolet light-emitting diodes (UV LED) have been broadly used for water disinfection but to date other applications are scarce. Due to public concern about the use of chemicals or thermal treatments modifying food characteristics, UV LEDs could be an alternative for microbial control.

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.