Research – Pulsed light treatment of dried parsley: reduction of artificially inoculated Salmonella spp. and impact in given quality parameters

Journal of Food Protection

Dried parsley is regularly contaminated with foodborne pathogens, especially Salmonella (S.) spp. Application of contaminated ingredients in ready-to-eat dishes without further thermal treatment represents a considerable health risk. This study examines the suitability of pulsed light as a novel decontamination method of Salmonella spp. in dried parsley, the impact on selected quality parameters (chlorophyll content, phenolic compounds, color, odor) and product characters (temperature, aw-value). Samples were inoculated with one of three Salmonella isolates (S. Cerro or one of two isolates of S. Agona) at two contamination levels of 103 or 107 CFU/g and treated under various experimental factors, including distance to the light source and exposure time, resulting in fluences in the range of 1.8 – 19.9 J/cm2. At selected parameter settings (9.8 and 13.3 J/cm2), the effect of prolonged storage time (48 h) of inoculated samples prior to treatment on the reduction of S. Cerro was examined. Samples treated at the same fluences were also stored for 35 days at 22 – 25 °C. The three Salmonella isolates were significantly reduced by pulsed light (p < 0.05). Reduction factors ranged between 0.3 – 5.2 log CFU with varying sensitivities of the isolates. In general, increasing fluences (depending on exposure time and distance to the light source) resulted in increasing reductions of Salmonella spp. However, on closer examination, exposure time and distance to the light source in detail had a varying influence on the reduction of the different Salmonella isolates. Decreasing reduction factors were observed by increasing the contamination level and prolonging storage time of inoculated samples prior to treatment. No undesirable changes in quality parameters and sensory analysis were detectable at fluences of 9.8 and 13.3 J/cm2, indicating that pulsed light may be a suitable alternative for the decontamination of dried parsley.

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