Purpose: To evaluate the efficacy of ultraviolet light against log and stationary phases of Listeria monocytogenes on bologna and its impact on quality and shelf life.
Methods: Listeria monocytogenes serotype 4a was cultured in Brain Heart Infusion (BHI) broth at 37°C. Cells were harvested at log and stationary phase, subjected to low (3–4 mW/sq. cm) and high (7-8 mW/sq. cm) intensity of UV. Listeria monocytogenes was inoculated on bologna followed by 30 min of attachment time; and then subjected to UV radiation from 0 to 300 s. Cells were recovered on Modified Oxford agar (MOX) after 24 h of incubation at 37°C. Additionally, shelf life along with quality attributes such as color and lipid oxidation (TBARS) were assessed over a period of 8 weeks on bologna stored at 0 and 4°C under vacuum.
Results: Populations of L. monocytogenes were significantly reduced (P < 0.05) after 150 s of UV exposure and subsequent reductions (P < 0.05) were observed up to 300 s irrespective of UV intensities. Higher (P < 0.05) reductions were observed in the log phase as compared to the stationary phase cells. Significant differences (P < 0.05) were observed in the L, a, b values at different storage temperature and exposure time over 8 weeks of storage. However, UV did not affect the lipid oxidation of bologna irrespective of the storage temperatures and time.
Significance: Significant reduction in L. monocytogenes population without affecting the quality attributes of bologna suggest the potential use of UV light as a post process intervention for RTE meats.