Process Parameters Affecting Listeria innocua Inactivation by Pulsed Light

The impact of several processing parameters on the effectiveness of pulsed light (PL) technology was investigated. The distribution of the light on the surface of the PL treatment chamber and the fluence striking on the sample under different treatment conditions were evaluated. Higher pulse fluences were registered when input voltage increased and the distance from the sample to the light source decreased. Distance from the sample to the xenon lamp also played a major role in the light distribution onto the surface of the treatment zone. Whereas quartz shelf placed close to the xenon lamp resulted in a non-uniform distribution of fluence, a homogeneous light distribution was found when increasing the distance to the flash lamp. Moreover, the impact of several PL processing parameters on microbial inactivation was investigated. Neither pulse voltage nor total voltage determined the antimicrobial effectiveness of PL technology in the operating range tested. Reduction in Listeria innocua counts increased with the number of pulses and the pulse fluence, being total fluence reaching the samples the most relevant process factor affecting microbial inactivation by PL. Considering the importance of this processing parameter, an accurate quantification of the fluence striking on the sample will be needed in order to design effective PL treatments.