title: Effect of chlorine, sodium chloride, trisodium phosphate, and ultraviolet radiation on the reduction of Yersinia enterocolitica and mesophilic aerobic bacteria from eggshell surface.
abstract: Eggshell sanitizing practices are necessary to improve microbiological safety of fresh hen eggs and their products. In this work, the effects of 100 mg/liter free chlorine (chl), 3% sodium chloride (NaCl), 1, 5, and 12% trisodium phosphate (TSP) in wash solutions, and UVR (ultraviolet radiation; 4.573 microW/cm2) were studied at different times on uninoculated and Yersinia enterocolitica-inoculated eggs. On uninoculated eggs, the best results were obtained with 100 mg/liter chlorine and UV exposure for >25 min, with reductions of 1.28 and 1.60 log cycles, respectively, compared to the average bacterial count (4.55 log CFU/egg) on the control (untreated eggs). On Y. enterocolitica-inoculated eggs, highest reductions of the average bacterial count (7.35 log CFU/egg) were obtained with 5 and 12% TSP and 100 mg/liter chl. The decrease obtained with 12% TSP (3.74-log reduction) was significantly higher (P < 0.05) than those obtained with the remaining treatments. Y. enterocolitica was more resistant to UVR than the eggshell natural mesophilic aerobic microflora, except when low inoculum (4.39 log CFU/egg) was assayed. Changes in eggshell microstructure were measured by the blue lake staining method. The presence of Yersinia and Salmonella in eggshell natural flora was also investigated.
authors.affiliation: Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, Argentina.
authors.forename: G L
authors.initials: GL
authors.lastname: Favier
authors.forename: M E
authors.initials: ME
authors.lastname: Escudero
authors.forename: A M
authors.initials: AM
authors.lastname: de Guzman
mesh_terms: D000818:Animals; D001420:Bacteria, Aerobic / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects; D002645:Chickens; D002713:Chlorine / Q000494:pharmacology; D015169:Colony Count, Microbial; D004202:Disinfectants / Q000494:pharmacology*; D004203:Disinfection / Q000379:methods*; D004528:Egg Shell / Q000382:microbiology*; D010710:Phosphates / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D014466:Ultraviolet Rays; D015008:Yersinia enterocolitica / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects
chemical_list: D004202:Disinfectants; D010710:Phosphates; D012965:Sodium Chloride; D002713:Chlorine; C018279:sodium phosphate