Inactivation of internalized Salmonella Typhimurium in lettuce and green onion using ultraviolet C irradiation and chemical sanitizers

Abstract

Aims: The internalized human pathogens in fresh produce are not effectively removed during conventional washing, and therefore, it may cause foodborne illness when the produce is consumed raw. Thus, effective nonthermal processes are needed to prevent this risk. Methods and Results: Green fluorescence protein-tagged Salmonella Typhimurium was either sprayed on the surface of iceberg lettuce or injected into the bottom part (bulb) of green onions to induce bacterial internalization. The contaminated vegetables were collected after 2 days and subjected to surface disinfection. Different fluencies of UV-C radiation (75-900 mJ cm À2 )and two fluencies of UV-C (450, 900 mJ cm À2 ) combined with chlorine and peracetic acid (PAA) were applied to the produce to examine the inactivation efficiency of internalized bacteria. A range of 1Á96-2Á52 log reduction in the internalized Salmonella was achieved when the lettuce was treated with higher UV-C fluency (150, 450, 900 mJ cm À2 ) or UV-C combined with chemical disinfectants. Significant reduction (1Á00-1Á49 log CFU g À1

Salmonella enterica Serovar Typhi and Paratyphi Responsible of Typhoid and Paratyphoid Fevers Transmitted by Environment and Food

“…For example using ultraviolet C irradiation and chemical sanitizers were very efficient to disinfected lettuce and fresh vegetable. Recent studies showed that ionizing radiation, such as gamma ray and electric beam, has been frequently examined for its potential of inactivating the internalized pathogens in fresh produce (Chimbombi et al 2011;Ge et al, 2013) and it was shown as an effective physical disinfectant to inactivate the human pathogens with low fluency in food without generating toxic hazards or making food radioactive, which has been confirmed by World Health Organization. Compared with the ionizing radiation methods, the application of ultraviolet light has grown steadily in various fields such as water, wastewater, aerosol, surface and food as its germicidal effect was firstly described by Ge et al (2013).…”

“…Foods susceptible to transport Salmonella include vegetable products such as lettuce. The fresh produce consumption is encouraged because of its health benefits; however, fresh produce can be contaminated with human pathogens in any stage of the food supply chain, which increases the risk of foodborne outbreaks (Lynch et al, 2009;Ge et al, 2013). Hygienic conditions are needed for these fresh produce for consumption to avoid contamination.…”

Occurrence of ingression of Salmonella spp. in Betel leaf (Piper betle L.)

“…Internalized bacteria can evade disinfection, thus detailed study on the mechanism of internalization as well as on plant and environmental factors affecting internalization is needed to devise remediation methods ensuring safety of the fresh produces (Ge et al 2013). Mechanism of internalization of bacteria in the plant has not been elucidated clearly till now.…”

Effects of gamma irradiation on the survival of Pseudomonas fluorescens inoculated on romaine lettuce and baby spinach

“…Other advantages of using irradiation in foods include its ability to eliminate food-borne pathogens or bacteria internalized in produce relative to chemical washes such as chlorine dioxide, sodium hypochlorite or other nonoxidizing agents which do not readily affect internalized microbes (Ge, Bohrerova, & Lee, 2013;Gomes, Da Silva, Moreira, & CastellPerez, 2009;Niemira, 2007;Shim et al, 2012). Irradiation has also been reported to extend the shelf life of produce and reduce quality losses in food or produce especially during short or longdistance transport in addition to its role in food safety (Prakash, Inthajak, Hulbregtse, Caporaso, & Foley, 2000).…”