Purpose: In this study, efficacy of pulsed light treatment for inactivation of Salmonella Montevideo on black pepper was investigated.
Methods: Black peppercorns (20 g) were dip-inoculated with 2 ml of Salmonella Montevideo and air dried for 24 h in a sterile environment. One-gram samples of peppercorns were vacuum packaged in polyethylene bags and then pulsed light treated for 10 to 40 s at a distance of 11.5 to 16.6 cm from the lamp at voltages of 3000 to 3800 V. Reduction in microbial population was enumerated by spread plating onto tropic soy agar with yeast extract.
Results: Increased treatment time increased microbial reduction. Reductions of 2.48, 3.79 and 5.37 log CFU/g were obtained at 20, 30 and 40 s, respectively, at a voltage of 3800 V and distance of 11.5 cm. Increased voltage also resulted in increased inactivation. Reductions of 0.57, 1.13 and 2.48 log CFU/g were obtained at 3000, 3400 and 3800 V, respectively, at 11.5 cm distance after 20 s treatment. Samples treated closer to the lamp were more readily inactivated. Reductions of 3.95, 2.55 and 0.63 log CFU/g were obtained at 11.5, 14.1 and 16.6 cm, respectively, after a 40 s treatment at 3400 V. The effect of treatment time, voltage, and distance were statistically different (P < 0.05).
Significance: These results suggest that pulsed light has potential for use for inactivating Salmonella on black pepper. Reductions up to 5.60 ± 0.46 log CFU/g were obtained within 40 s indicating that pulsed light can provide rapid decontamination of black peppercorns packaged in the final package.